REESE  LIBRARY 
UNIVERSITY  OF. CALIFORNIA. 


r 


AN 


INTRODUCTION 


TO 


ENTOMOLOGY 


BY 

JOHN    HENRY  COMSTOCK 

PROFESSOR    OF    ENTOMOLOGY    AND    GENERAL    INVERTEBRATE    ZOOLOGY 
IN    CORNELL    UNIVERSITY 

AND  FORMERLY 
UNITED    STATES    ENTOMOLOGIST 


WITH  MANY  ORIGINAL    ILLUSTRATIONS 

DRA\fN  AND    ENGRAVED    BY 

. 

ANNA   BOTSFORD    COMSTOCK 


ITHACA,  N.  Y. 
PUBLISHED    BY    THE    AUTHOR 

1888 


*»¥• ' 


COPYRIGHT,  1888, 
BY  JOHN  HENRY  COMSTOCK. 


UBK4&X 

or  THE        '     \ 

(UNIVERSITY) 
^ 


PREFACE  TO  PART  L 


THIS  work  has  been  prepared  to  meet  the  demand  for  a  text- 
book which  shall  enable  students  to  acquire  a  thorough  knowledge 
of  the  elementary  principles  of  Entomology,  and  to  classify  in- 
sects by  means  of  analytical  keys  similar  to  those  used  in  Botany. 
By  means  of  the  keys  the  student  can  readily  determine  to  what 
family  any  insect  of  which  he  has  a  specimen  belongs.  In  many 
cases  tables  of  genera  are  also  given ;  and  the  more  common  or 
conspicuous  species  in  each  family  have  been  described. 

Although  much  pains  has  been  taken  to  render  easy  the  classifi- 
cation of  specimens,  an  effort  has  been  made  to  give  the  mere  deter- 
mination of  the  names  of  insects  a  very  subordinate  place.  The 
groups  of  insects  have  been  fully  characterized,  so  that  their  relative 
affinities  may  be  learned ;  and  much  space  has  been  given  to 
accounts  of  the  habits  and  transformations  of  the  forms  described. 
As  the  needs  of  Agricultural  students  have  been  kept  constantly 
in  view,  those  species  that  are  of  economic  importance  have  been 
described  as  fully  as  practicable,  and  particular  attention  has  been 
given  to  descriptions  of  the  methods  of  destroying  those  that  are 
noxious,  or  of  preventing  their  ravages. 

The  pronunciation  of  the  technical  terms  has  been  indicated  by 
marking  the  accented  vowel,  and  at  the  same  time  indicating  its 
length  when  the  term  is  pronounced  as  an  English  word. 

All  the  illustrations  not  credited  to  other  sources  are  original, 
and  have  be.  n  and  engraved  by  Mrs.  Comstock. 

The  specimens  that  have  been  studied  in  the  preparation  of  this 
work  are  nearly  all  in  the  collections  of  the  Entomological  Depart- 


IV  PREFACE    TO  PART  I. 

ment  of  Cornell  University.  That  these  collections  are  in  a  suffi- 
ciently good  condition  for  this  purpose  is  due  very  largely  to  the 
generous  assistance  of  many  Entomologists.  Specific  acknowledg- 
ments will  be  made  later. 

As  the  completion  of  the  work  has  been  delayed  by  other  duties, 
it  has  seemed  best  to  issue  this  part  at  this  time.  Other  chapters 
will  be  published  as  soon  as  practicable.  In  addition  to  the  system- 
atic part,  the  scope  of  which  can  be  inferred  from  that  given  here, 
there  are  to  be  chapters  on  the  Means  of  Destroying  Insects  or  of 
Preventing  their  Ravages,  the  Collection  and  Preservation  of  Ento- 
mological Specimens,  Entomological  Supplies,  a  Classified  List  of 
Entomological  Works,  a  Glossary,  and  an  Introductory  Chapter. 

JOHN  HENRY  COMSTOCK. 

ENTOMOLOGICAL  LABORATORY,  CORNELL  UNIVERSITY, 
September,  1888. 


AN    INTRODUCTION   TO   ENTOMOLOGY 


CHAPTER   I. 

THE  CHARACTERS  AND  METAMORPHOSES  OF  INSECTS 
(HEXAPODA). 

I.    THE  CHARACTERS  OF  THE  HEXAPODA. 

THE  term  Insect  is  from  two  Latin  words  —  in,  in,  and  seco,  to  cut. 
It  refers  to  the  fact  that  in  the  animals  indicated  by  it  the  body  is 
divided  by  transverse  incisions  into  a  series  of  segments.  As  has 
been  shown  in  the  Introductory  Chapter,  this  insected  form  of  the 
body  is  characteristic  of  two  of  the  larger  divisions  of  the  Animal 
Kingdom,  the  Vermes,  or  Worms  and  the  Arthropoda.  But  the  term 
Insect  has  become  restricted  to  a  portion  of  this  great  series  of  ani- 
mals. There  is,  however,  a  lack  of  uniformity  in  the  use  of  the  term 
among  zoological  writers.  By  some  it  is  applied  to  all  Arthropoda 
that  breathe  by  means  of  a  system  of  air-tubes  (tracheae)  extending 
throughout  the  body.  This  includes  Centipedes,  Millepedes,  Spiders 
and  allied  forms,  as  well  as  the  six-footed  insects.  Other  writers  in- 
clude among  Insects  only  those  orders  which  are  characterized  by 
the  possession  of  but  six  legs.  It  is  in  this  restricted  sense  that  I 
have  used  the  term  Insect.  Whenever  reference  is  made  to  all  of  the 
Arthropoda  that  breathe  by  means  of  tracheae,  they  are  designated 
as  the  Trachedta. 

Insects,  in  the  restricted  sense  indicated  above,  constitute  the 
class  HEXAPODA.*  The  insected  or 
segmented  form  of  the  body  is  shown 
in  Fig.  i,  and  in  nearly  all  of  the 
species  figured  in  the  following  pages. 
The  peculiar  structure  of  the  respira- 
tory system,  which  is  characteristic  of 
these  animals,  and  which  allies  them 
to  other  Tracheata,  is  described  in  the  next  chapter.  In  the  Hexapoda 


FlG>  I(_Nymph  of  the  Red.le{rged  Locust. 
(After  Emenon  •> 


*Hexapoda  :  hex  (e%),  six;  pous  (itovS),  a  foot. 


AN  INTRODUCTION   TO  ENTOMOLOGY. 

the  typical  adult   is  furnished   with  six  legs ;  the  segments  of  the 

body  are  grouped  into  three  regions,  head, 
thorax,  and  abdomen,  Fig.  2 ;  and  the 
body  is  usually  furnished  with  wings. 
Exceptions  to  each  of  these  characteristics 
occur.  The  more  important  of  these  ex- 
ceptions are  discussed  in  the  course  of  the 
following  chapters. 

FIG.  *.-Monobia.        jj       JRE    METAMORPHOSES    OF    INSECTS. 

Among  the  marvellous  facts  revealed  by  the  study  of  insects, 
none  is  more  striking  than  the  wonderful  transformations  which  many 
of  these  creatures  undergo.  A  large  part  of  this  book  is  devoted  to 
indicating  these  changes.  In  this  chapter  I  wish  simply  to  make 
a  few  generalizations  regarding  the  metamorphoses  of  insects,  and 
to  define  a  few  terms  which  are  used  in  describing  these  changes. 

Complete  Metamorphosis.  —  From  the  egg  of  a  butterfly  there 
emerges  a  worm-like  creature,  known  as  a  caterpillar,  which  has  upon 
superficial  examination  very  little  in  common  with  its  parents.  This 
caterpillar  eats  and  grows,  and  when  fully  grown  changes  to  an  ob- 
long, apparently  lifeless  object,  the  chrysalis.  After  a  time  there 
bursts  forth  from  this  chrysalis  a  butterfly,  like  that  which  produced 
the  egg.  In  a  similar  way,  from  the  egg  laid  by  a  fly  upon  a  piece 
of  meat  there  hatches,  not  a  fly,  but  a  footless,  worm-like  maggot. 
This  when  fully  grown  changes  to  a  quiescent  object  corresponding 
to  the  chrysalis  of  the  butterfly.  I^ater  from  this  object  there 
escapes  a  winged  fly  like  that  which  laid  the  egg.  Those  insects, 
like  the  butterflies  and  flesh-flies,  which  when  they  emerge  from 
the  egg  bear  almost  no  resemblance  in  form"  to  the  adult  insect 
are  said  to  undergo  a  complete  metamorphosis.  In  other  words,  the 
change  of  form  undergone  by  the  insect  is  a  complete  one. 

Incomplete   Metamorphosis. — There   are,  however,  many   in 
which  after  leaving  the  egg  do  not  undergo  such  a  remarkable  ch 
of  form  as  that  indicated  above.    A  young  grasshopper  just  out  from 
the  egg  can  be  easily  recognized  as  a  grasshopper.     It  is  of  course 
much  smaller  than  the  adult,  and  is  not  furnished  with  wings.     Still 
the  form  of  the  body  is  essentially  the  same  as  that  of  an  adult. 
After   a   time    rudimentary  wings   appear;    and   these   increase   in 
size    from    time  to    time    till    the  adult  state  is  reached.       During 
this    development    there    is   no    point   at  which    the    insect   passes 


THE   CHARACTERS  AND  METAMORPHOSES  OF  INSECTS. 


into  a  quiescent  state  corresponding  to  the  chrysalis  state  of  the 
butterfly.  Those  insects  which,  like  the  grasshoppers,  when  they 
emerge  from  the  egg  resemble  in  form  the  adult  are  said  to  undergo 
an  incomplete  metamorphosis.  In  other  words,  after  leaving  the  egg 
they  do  not  undergo  a  complete  change  of  form. 

Moulting,  Exuvicz. — The  body-wall  of  an  insect  is  rendered  more 
or  less  hard  by  the  deposition  within  its  cuticular 
layer  of  a  horny  substance  known  as  chitine. 
The  result  of  this  hardening  of  the  skin  is  to 
render  it  inelastic.  Consequently  as  the  body  of 
an  insect  increases  in  size  its  skin  becomes  too 
small  for  it.  When  this  occurs  a  second  soft  skin 
is  formed  beneath  the  outer  hard  one.  Then  the 
outer  skin  splits  open,  usually  along  the  back,  and 
the  insect  works  itself  out  from  it.  The  new  skin 
being"  elastic  accommodates  itself  to  the  increased 

o 

size  of  the  body.  In  a  short  time  this  new  skin 
becomes  hardened ;  and  as  the  insect  grows,  it  in 
turn  is  cast  off.  This  shedding  of  the  skin  is 
termed  moulting  or  ecdysis.  The  cast  skins  are 

6  FIG.  3.— Exuviae  of  a 

sometimes  referred  to  as  the  cxfivice.    The  number          Dragon-fly. 

of  moults  varies  greatly  in  the  different  groups  of  insects.     In  Fig. 

3  is  shown  the  cast  skin  of  a  dragon-fly  clinging  to  a  reed. 

The  Egg. — The  egg  is  the  first  of  the  four  principal  stages  through 

which  an  insect  passes  in  the  course  of  its  development.     In  a  few 

instances  the  egg  is  retained  within 'the  body  of  the  female  until 

after  it  is  hatched;  in  this  case  the  in- 
sect is  said  to  be  viviparous.  An  ap- 
parent exception  to  the  rule  that  all 
insects  are  produced  from  eggs  is  pre- 
sented by  certain  generations  of  the 
Plant-lice  (Aphidida).  This  is  discussed 
in  the  description  of  that  family.  The 
eggs  of  insects  vary  greatly  in  their 
external  characters.  While  many  of 
them  are  furnished  with  smooth  oval 
shells,  in  others  the  shells  are  beautiful- 
ly ribbed,  or  pitted  (Fig.  4),  or  furnished 
with  spines  or  other  appendages.  There 
exists  also  in  one  end  of  the  egg  of  an 
in  ct  one  or  m$re  pores  known  as  mlcropyles ;  through  these  the 


FIG.  4. — Egg  of  Cotton-worm,  great! 
enlarged.  (From  thd  Author's  Kepo 
on  Cotton  Insects.) 


ready 
rt 


4  AN  INTRODUCTION   TO  ENTOMOLOGY. 

spermatozoa  pass  into  the  egg,  and  thus  fertilize  it.  Many  of  the 
interesting  exhibitions  of  instinctive  powers  which  I  have  described 
in  the  following  pages  are  connected  with  the  care  of  their  eggs 
by  insects. 

The  Larva. — The  larva  is  the  second  of  the  four  principal  stages 
in  the  life  of  an  insect.     It  is  the  stage  in  which 
an  insect  emerges  from  the  egg.     Familiar  ex- 
amples of  larvae  are  caterpillars,  maggots,  grubs, 

/T^.  x          T,    •         i        •  ,1          1  ^i       L     FlG-  5-— . 

etc.  (Fig.  5).     It  is  during  the  larval  state  that      (From  the  Author's  Re- 
port for  1879.) 

the  growth   of  the  insect  is  made  ;  and   conse- 
quently in  this  stage  nearly  all  the    moults   are    undergone.     The 
moults  subsequent  to  this  period  are  simply  those  made  when  the 
insect  changes  from  one  stage  to  another. 

Nearly  all  of  the^creatures  commonly  known  as  worms  are  not 
true  worms,  but  are  the  larvae  of  insects.  Away  from  the  sea-shore 
but  few  worms  are  known  to  other  than  zoologists ;  these  are 
earth-worms,  Jeeches,  hair-worms,  and  the  various  species  parasitic 
in  the  bodies  of  higher  animals.  The  many  worm-like  animals 
found  feeding  upon  the  tissues  of  plants,  as  tomato-worms,  apple 
worms,  etc.,  are  the  larvae  of  insects.  Other  larvae  of  insects  are 
predaceous  or  parasitic. 

The  Pupa. — The  pupa  is  the  thircVof  ihe  four  stages  in  the  life  of 

an  insect.  In  this  stage  the  insect  is 
usually  quiescent.  But  a  few  pupae, 
as  those  of  mosquitoes,  are  active. 
The  change  from  the  larva  to  the 
pupa  state  is  made  by^moulting  the 
skin  of  the  fully  grown  larva.  In  the 

FIG.  6.—  Pupa  of  Platysamia,  .         . 

pupa  the  legs  and  wings  of  the  adult 

are  represented  in  a  rudimentary  state.  In  the  pupae  el  butterflies  and 
moths  these  organs  are  closely  soldered  to  the  breafst  of  the  insect 
(Fig.  6),  while  in  the  pupae  o.  bees,  wasps,  and  beetles  they  are 
free.  , 

Chrysalis. — The  term  chrysaUs  is  applied  to  the 'pupa  of  a  but- 
terfly. This  name  was  suggested  by  the  bright,  metallic  spots 
with  which  the  pupae  of  certain  butterflies  are  markfd.  Two  forms 
of  this  word  are  in  use:  chrysalis,/'  chrysalides;  and  chrysalid,//. 
chrysalids. 

The  Cocoon. — Many  larvae,  as  those  of  moths,  when  fully  grown,* 
and  before  they  change  to  pupae,  spin  about  the  body  a  silken  case, 


THE    CHARACTERS  AND  METAMORPHOSES  OF  INSECTS. 


within   which    the    transformations   are   undergone.      This   case    is 

termed  a  cocoon.    Frequently  these 

cocoons  are  made  within  a  rolled 

leaf  (Fig.  7),  or  on  the  surface  of 

the  ground,  where  they  are  covered 

with  dry   grass  or  other    rubbish. 

Certain    hairy    caterpillars     make 

their  cocoons  largely  of  their  hair, 

which  they  fasten   together  by  a 

thin  film  of  silk. 

Immature  Forms  of  Insects  with  Incomplete  Metamorphosis,   The 
Nymph. — The  terms  larva  and  pupa  are  applicable  only  to  the  early 


FIG.  7.— Cocoon  of  Telia. 


FIG.  8.— Nymph  of  Melanoplus,  first  stage. 
(After  Emerton.) 


FIG.  9. — Nymph  of  Melanoplus,  second  stage. 
(After  Emerton.) 


stages  of  insects  with  a  complete  metamorphosis.  In  the  case  of 
.those  in  which  the  transformation  is  an  incomplete  one,  the  changes 
through  which  the  immature  insect  passes  after  leaving  the  egg  are 


FIG.  10. — Nymph  of  Melanoplus,  third  stage. 
(After  Emerton.) 


FIG.  ii.— Nymph  of  Melanoplus,  fourth  stage, 
(After  Emerton.) 


so  gradual  that  one  cannot  indicate  any  point  at  which  the  insect 
ceases  to  be  a  larva  and  becomes  a  upa.  Recent  writers  have  used, 
therefore,  the  term  nymph  (a  term  formerly  used  as  a  synonym  of 
pupa)  to  designate  the  immature  forms  of  insects  with  an  incomplete 
metamorphosis.  This  term  is  i  -'plied  to  all  the  stages  between  the 
egg  and  the  fully  winged  or  adujt  state. 

A  nymph  when  it  leaves  the -egg  has  no  indications  of  wings. 
After  undergoing  a  greater  or  1e?s  number  of  moults,  differing  in 
different  species,  small  prolongations  appear  projecting  from  the 


6  AN  INTRODUCTION   TO  ENTOMOLOGY. 

dorsal  aspect  of  the  meso-  and  metathorax.     These  become  larger 
and  larger  with  each  successive  moult,  assuming  the  form   of  pad- 


FIG.  12. — Nymph  of  Melanoplus,  fifth  stage. 
(After  Emerton.) 


FIG.  -L^.—Melanoplus,  adult. 


like  wing-cases.  But  these  wing-cases  never  approximate  in  length 
the  perfect  wings  of  insects  in  which  these  organs  become  fully 
developed.  There  is,  therefore,  usually  a  very  marked  change 
between  the  last  nymph  stage  and  the  mature  insect.  (See  Figs. 
12  and  13.) 

With  the  nymphs  of  certain  families,  dragon-flies,  crickets,  grass- 
hoppers, and  locusts,  the  wing-cases  are  inverted  ;  i.e.,  the  aspect  cor- 
responding to  the  upper  side  of  the 'wing  is  next  to  the.  body,  and 
the  first  pair  of  wing-cases  extend  back  beneath  the  second  pair. 
This  characteristic  is  useful  in  distinguishing  the  adult  forms  from 
the  nymphs  of  those  species  in  which  the  wings  never  become  fully 
developed. 


THE  ANATOMY  OF  INSECTS. 


CHAPTER   II. 
THE   ANATOMY   OF   INSECTS. 

THE  subject  of  insect  anatomy  is  separated  into  two  divisions : 
one,  treating  of  the  structure  of  the  body-wall  or  skeleton  ;  the  other, 
of  the  internal  organs.  The  former  is  termed  external  anatomy  ;  the 
latter,  internal  anatomy. 

THE  EXTERNAL  ANATOMY  OF  INSECTS.* 

The  relative  positions  of  the  more  important  parts  of  the  body  of 
insects  can  be  easily  comprehended  by  recalling  what  has  been  said, 
in  the  Introductory  Chapter,  regarding  the  type  of  structure  pre- 
sented by  the  Arthropoda.  In  this  branch  of  the  Animal  Kingdom, 
which  includes  insects,  the  body  is  an  elongated  cylinder  composed 
of  many  rings  (Fig.  14).  A  cross-section  of  the  body  shows  it  to  be 


FIG.  14. — Diagram  of  structure  of  Arthropoda. 

a  tube  within  which  are  the  various  viscera, — muscles,  alimentary 
canal,  heart,  nervous  system,  reproductive  organs,  etc.  The  tubular 
body-wall,  being  hardened  and  furnishing  support  to  the  softer  or- 
gans, is  the  skeleton.  This  hardening  of  the  body-wall  is  due  to  the 
deposition  in  it  of  some  hard  substance.  In  insects  the  substance 
thus  deposited  is  horny,  and  is  termed  chltine. 

Between    certain  rings  or  segments  of  the  body  the  body-wall 

remains  soft  and  flexible.     In  this  way  provision   is  made  for  the 

various  notions  of  the  body.     The  ring-like  nature  of  the  segments 

is  best  seen  in  larvae,  and  in  the  caudal  part  of  adult  insects.     In  the 

iephaUc  pait  of  adult  insects  it  is  less  obvious. 

When  a  single  segment  of  the  body  is  examined,  the  hardened 
portion  is  not  found  to  be  a  continuous  ring,  but  is  seen  to  be  made 
up  of  several  portions  more  or  less  movable  upon  each  other.  Such 
a  hardened  portion  of  the  body-wall  is  termed  a  sclcrite. 

*  See  Tabular  Review  at  the  end  of  this  part  of  this  chapter  for  an  explanation  of  the 
lettering  of  the  illustrations. 


AN  INTRODUCTION    TO  ENTOMOLOGY, 

The  sclerites  constitute  the  greater  part  of  the  body-wall,  the  soft 
membranous  portions  separating  them  being  in  most  cases  narrow. 

Usually  these  narrow  portions  are  mere 
lines  ;  they  are  then  called  siititres. 

Frequently  the  sutures  become  en- 
tirely effaced.  We  are  therefore  often 
unable  to  distinguish  certain  sclerites 
in  one  species  of  insect  which  we  know 
to  exist  in  another.  In  such  cases  the 
effaced  sutures  are  said  to  be  obsolete. 
FIG.  15.— Poiistes  beiiicosa.  The  segments  of  the  body  in  a  fully 

developed  insect  are  grouped  into  three  regions :  head,  thorax,  and 
abdomen  (Fig.  i  5).  In  the  larval  state  this  grouping  of  the  segments 
is  not  well  shown. 

The  Head. 

The  head  is  the  first  of  the  three  regions  of  the  body.  It  is  sup- 
posed to  be  formed  of  several  body-segments  grown  together ;  but 
entomologists  differ  in  their  views  as  to  the  number  of  segments 
that  have  entered  into  its  composition. 

It  does  not  fall  within  the  scope  of  this  work  to  enter  into  this  discussion. 
The  main  point,  however,  can  be  stated  here.  A  careful  study  of  the  various 
forms  of  Arthropods  shows  that  the  typical  body-segoient  possesses  a  pair  of 
legs,  and  only  one  pair.  It  is  known  that  certain  mouth  parts  (mandibles, 
maxillae,  and  labium)  are  modified  legs.  (This  fact  is  easily  seen  in  many 
Crustacea.)  The  antennae  and  the  eyes  may  also  be  modified  legs.*  It  follows 
that  if  we  find  represented  in  the  appendages  of  the  head  the  appendages  of 
several  segments,  the  head  itself  must  consist  of  several  segments  coalesced. 

The  principal  portion  of  the  chitinized  parts  of  the  head  are  firm- 
ly joined  together  so  as  to  constitute  a  box  which  contains  the  brain 
of  the  insect  and  certain  other  important  organs.  To  this  are  artic- 
ulated a  number  of  jointed  appendages.  The  parts  of  the  head 
may  be  classed,  therefore,  under  two  divisions  :  first,  the  fixed  parts ; 
second,  the  movable  parts. 

The  Fixed  Parts  of  the  Head. 

In  addition  to  the  external  portions  of  the  organs  of  vision  (the 
compound  eyes,  and  the  simple  eyes),  the  fixed  parts  of  the  head 
consist  of  four  sclerites.  Three  of  these  sclerites  (occiput,  epicra- 

*  The  belief  that  the  eyes  are  modified  legs  is  based  on  the  fact  that  in.certain  Crusta- 
cea the  eyes  are  situated  on  stalks  which  are  jointed  appendages  of  the  head. 


THE  ANATOMY   OF  INSECTS.  g 

nium,  and  clypeus)  pertain  to  the  dorsal  surface ;  and  the  fourth 
(gula)  to  the  ventral  surface. 

Frequently  the  sutures  between  some  of  these  sclerites  are  obso- 
lete ;  but  by  studying  a  series  of  insects  each  of  these  parts  can  be 
distinguished. 

The  Compound  Eyes. — In  many  insects  the  most  striking  in  appear- 
ance of  the  fixed  parts  of  the  head  are  the  eyes  (3).*  These  are 
situated  one  on  each  lateral  aspect  of  the 
head.  They  are  usually  nearly  hemispherical 
and  of  considerable  size.  When  examined  with 
a  microscope,  they  present  the  honey-comb- 
like  appearance  shown  in  Fig.  16.  Each  of 
the  hexagonal  divisions  of  the  eye  is  a  cornea 
of  a  distinct  eye.  These  large  eyes  are  there-  FIG.  16.— Part  of  compound  eye, 

J    .  '  J  greatly  enlarged. 

fore  compound.     Each  of  the  small  eyes  of 

which  they  are  com1^          s  termed  an  ocellus.     Compound  eyes  are 

not  found  in  1 

T*  Ryes. — In  addition  to  the  compound  eyes,  many  insects 

ipie  eyes  (4).     These  are  situated  in  adult  insects  on  the 

,ai  aspect  of  the  head  between  the  compound  eyes,  and  in  larvae 
on  the  sides  of  the  head.  They  vary  in  number  in  the  adult  from 
one  to  four.  The  most  common  number  is  three;  see  Fig.  15. 
Each  simple  eye  resembles  an  ocellus  of  a  compound  eye.  The 
simple  eyes  are  usually  termed  ocelli;  sometimes,  stemmata. 

When  the  term  ocelli  is  used  in  descriptive  works,  if  there  is  noth- 
ing in  the  context  to  indicate  the  contrary,  it  is  almost  invariably 
applied  to  the  simple  eyes,  and  not  to  the  elements  of  the  compound 
eyes.  In  the  same  way  the  term  eye  usually  refers  to  the  compound 
eyes,  unless  otherwise  indicated  bM^the  context. 

The  Epicranium. — The  epicranium  (2)  is  usually  the  largest  of  the  three 
sclerites  which  pertain  to  the  dorsal  aspect  of  the  head.  It  is  that  sclerite  in 
which  the  simple  eyes  are  situated,  and  which  surrounds  the  compound  eyes. 
It  occupies  an  intermediate,  position  in  the  dorsal  aspect  of  the  head,  being 
bounded  caudadt  by  the  occiput,  and  cephalad  by  the  clypeus. 

From  the  fact  that  the  epicranium  occupies  so  large  a  part  of  the  head,  it 
frequently  becomes  necessary  to  speak  of  particular  regions  of  it  in  making 
detailed  descriptions  of  insects.  Consequently  names  have  been  given  to  cer- 
tain parts  ;  although  those  parts  are  very  rarely  distinct.  These  names  are 
front,  vertex,  and  genes.  It  is  difficult  to  define  definitely  the  regions  of  the 
epicranium  to  which  these  terms  have  been  applied.  Roughly  speaking,  the 


*  See  Tabular  Review  at  end  of  discussion  of  External  Anatomy. 

f  For  definitions  of  the  terms  denoting  position  and  direction  of  parts,  see  Glossary, 


10  AN  INTRODUCTION   TO  ENTOMOLOGY. 

front  (20)  is  the  cephalic  portion  of  the  epicranium  (Fig.  17).     It  is  bounded 

cephalad  by  the  clypeus,  and  laterad  by  the  eyes 
and  gense.  The  vertex  \2b}  is  the  remaining  part 
of  the  dorsal  portion  of  the  epicranium  ;  it  ex- 
tends from  between  the  eyes  to  the  occiput.  By 
many  writers  the  term  vertex  is  used  in  a  vague 
manner  to  indicate  the  summit  of  the  head. 
The  gencp  (T.C)  or  cheeks  are  the  lateral  portions 
of  the  epicranium,  those  parts  which  are  usually 

ventrad  of  the  eyes  and  caudad  of  the  mandibles.     In  many  insects  a  distinct 

suture  extends  cephalad  from  each  compound  eye,  separating  the  front  from 

the  genae. 

The  Occiput. — The  occiput  (i)  is  that  part  of  the  dorsal  wall  of  the  head 

which  is  articulated  with  the  cephalic  margin  of  the  thorax  (Fig.  18).     In  many 


FIG.  18. — Dorsal  aspect  of  head  of  Harpalus,  FIG.  ig.  -  '  I          ead-of  Harpalus. 

insects  it  is  a  distinct  sclerite  ;  in  others  it  is  not  distingu^ 
cranium. 

The  Clypeus. — The  clypeus  (5)  is  the  cephalic  part  of  the  dorsal  portiv,. 
the  fixed  parts  of  the  head.     It  is  bounded  caudad  by  the  epicranium,  and 
gives  attachment  cephalad  to  one  of  the  movable  parts  of  the  head,  the  labrum 
or  upper  lip.     The  clypeus  is  typically  composed  of  two  sclerites.     When  these 
are  distinct  they  are  designated  as  the  ante-clypeus  and  post-clypeus  respectively. 

The  Gula. — The  gula  (6)  is  the  only  one  of  the  fixed  parts  of  the  head  that 
is  confined  to  the  ventral  aspect  (Fig.  19).  It  is  bounded  laterad  by  the  lateral 
parts  of  the  epicranium  and  occiput ;  and  extends  caudad  to  the  caudal  border 
of  the  head.  Cephalad  it  gives  attachment  to  one  of  the  movable  parts  of  the 
head,  the  labium  or  lower  lip. 

The  Movable  Parts  of  the  Head. 

Under  this  category  are  classed  a  pair  of  jointed  appendages 
termed  the  antennce,  and  the  organs  known  collectively  as  the  mouth- 
parts. 

The  Antennce. 

The  antenncz  (7)  are  a  pair  of  jointed  appendages,  inserted  in  the 
head  in  front  of  the  eyes  or  between  them.  They  vary  in  form. 
In  some  insects  they  are  thread-like,  consisting  of  a  series  of  similar 
segments  ;  in  others  certain  segments  are  greatly  modified  in  form. 
In  the  beetles  of  the  genus  Collops  the  antennae  bear  a  curious  articu- 
lated appendage  arising  from  near  the  base  of  the  third  segment.* 


*  Horn,  Trans.  Am.  Ent.  Soc.,  III.  p.  79,  with  figure. 


THE-  ANATOMY  OF  INSECTS. 


II 


In  descriptive  works  names  have  been  given  to  particular  parts  of  the  anten- 
nae, as  follows  (Fig.  20) : 

The  Scape. — The  first  or  proximal  segment  of  an  antenna  is  called  the  scape 
(a).  The  proximal  end  of  this  segment  is  often 
subglobose,  appearing  like  a  distinct  segment ;  in 
such  cases  it  is  called  the  bulb. 

The  Pedicel. — The  pedicel  (£)  is  the  second 
segment  of  an  antenna.  In  some  insects  it  differs 
greatly  in  form  from  the  other  segments. 

The  Clavola. — The  term  clavola  (c)  is  applied 
to  that  part  of  the  antenna  distad  of  the  pedicel ; 
in  other  words,  to  all  of  the  antenna  except  the 
In  some  insects  certain  parts  of  the  clavola  are 
These  are  the  ring-joints,  the 


FIG.  20. — Antenna  of  Chalcis-fly. 


first  and  second  segments. 

specialized  and  have  received  particular  names. 

funicle,  and  the  club. 

The  Ring-joints. — In  certain  insects  (e.g.)  Chalcididae)  the  proximal  segment 
or  segments  of  the  clavola  are  much  shorter  than  the  succeeding  segments  ;  in 
such  cases  they  have  received  the  name  of  ring-joints  (V1). 

The  Club. — In  many  insects  the  distal  segments  of  the  antennae  are  more  or 
less  enlarged.  In  such  cases  they  are  termed  the  club  (c*). 

The  Funicle. — The  funicle  (V2)  is  that  part  of  the  clavola  between  the  club 
and   the   ring-joints  ;    or,    when  the  latter  are  not 
specialized,  between  the  club  and  the  pedicel. 

The  various  forms  of  antennae  are  designated  by 
special  terms.  The  more  common  of  these  forms 
are  represented  in  Fig.  21.  They  are  as  follows: 

1.  Setaceous   or  bristle-like,    in   which  the  seg- 
ments  are    successively  smaller  and   smaller,   the 
whole  organ  tapering  to  a  point. 

2.  Filiform  or  thread-like,   in   which   the  seg- 
ments are  of  nearly  uniform  thickness. 

3.  Moniliform    or   necklace-form,  in   which  the 
segments   are   more  or  less   globose,  suggesting  a 
string  of  beads. 

4.  Serrate  or  saw-like,  in  which  the  segments  are 
triangular  and  project  like  the  teeth  of  a  saw. 

5.  Pectinate  or  comb-like,  in  which  the  segments 
have  long  processes  on  one  side,  like  tne  teeth  of  a 
comb. 

6.  Cldvate  or  club-shaped,  in  which  the  segments 
become  gradually  broader,  so  that  the  whole  organ 
assumes  the  form  of  a  club. 

7.  Capitate  or  with  a  head,  in  which  the  terminal  segment  or  segments  form 
a  large  knob. 

8.  Ldmellate,  in  which  the  segments  that  compose  the  knob  are  extended 
on  one  side  into  broad  plates. 


FIG.  21. — Various  forms  of  an- 
tennae. 


12 


AN  INTRODUCTION   TO  ENTOMOLOGY. 


FIG.  22. — Mouth -parts  of  the  Red- 
legged  I^ocust. 


The  Mouth-parts. 

The  mouth-parts  (Fig.  22)  consist  typically  of  an  upper  lip,  labrum 
(8),  an  under  lip,  labium  (12),  and  two 
pairs  of  jaws  acting  horizontally  between 
them.  The  upper  pair  of  jaws  are  called 

,.,,  ^    ^Ja^  the   mandibles  (10);    the    lower   pair,  the 

lfc|»  maxillce  (11).  The  maxillae  and  labium 
are  each  furnished  with  a  pair  of  feelers, 
called  respectively  the  maxillary  palpi 
(nd\  and  the  labial  palpi  (\2d\  There 
may  be  also  within  the  mouth  one  or  two 
tongue-like  organs,  the  epipharynx  (9)  and 
hypopharynx  (13). 

No  set  of  organs  in  the  body  of  an  insect 
vary  in  form  to  a  greater  degree  than  do  the 
mouth-parts.  Thus  with  some  the  mouth  is 
formed  for  biting,  while  with  others  it  is  formed 
for  sucking.  Among  the  biting  insects  some  are  predaceous,  and  have  jaws 
fitted  for  seizing  and  tearing  their  prey ;  others  feed  upon  vegetable  matter, 
and  have  jaws  for  chewing  this  kind  of  food.  Among  the  sucking  insects 
the  butterfly  merely  sips  the  nectar  from  flowers,  while  the  moscjuito  needs  a 
powerful  instrument  for  piercing  its  victim.  In  this  chapter  the  typical  form 
of  the  mouth-parts  as  illustrated  by  the  biting  insects  is  described.  The 
various  modifications  of  it  presented  by  the  sucking  insects  are  described  later, 
in  the  discussions  of  the  characters  of  those  insects.* 

The  Labrum. — The  labrum  or  upper  lip  (8)  is  an  appendage  of  the  cephalic 
margin  of  the  dorsal  part  of  the  head.  It  is  usually  a  narrow  transverse  sclerite. 
In  some  insects  it  is  large  and  projecting,  and  often  notched  ;  in  others  it  is 
concealed  beneath  a  largely  developed  clypeus. 

The  Mandibles. — The  mandibles  (10)  are  the  dorsal  pair  of  jaws.  They  vaiy 
much  in  form,  but  are  usually  three-sided,  with  their  lateral  t  surface  more  or 

*  The  more  important  papers  on  the  nomenclature  of  the  parts  of  the  mouth  in  biting 
insects  are  the  following: 

KIRBY  AND  SPENCE.     Introduction  to  Entomology,  vol.  III.    (1818.) 

MACLEAY,  W.  S.  Horse  entomologicae  (2  vols.,  1819,  1821).  This  work  I  have  not 
seen. 

STRAUS-DURCKHEIM,  H.  E.  Considerations  generate  sur  1'anatomie  des  animaux 
articules.  (1828.) 

NEWMAN,  EDWARD.     A  paper  on  the  nomenclature  of  the  parts  of  the  head  of  insects. 

(1834.) 

NEWPORT,  G.     The  article  "  Insecta,"  Todd's  Cycl.  of  Anat.  and  Physio).     (1839.) 
BRULLE,  A.     Recherches  sur  les  transformations  des  appendices  dans  les  Articules. 

Annales  des  Sciences  Naturelles,  t.  II.    (1844.) 

f  I  have  not  attempted  to  determine  the  normal  position  of  the  mouth-parts,  but  have 

described  each  with  its  distal  end  directed  cephalad.     This  seems  to  me  the  way  least 

likely  to  lead  to  confusion. 


THE  ANATOMY  OF  INSECTS. 


less  convex,  and  their  mesal  surface  concave.  Usually  each  mandible  consists 
of  a  single  segment;  but  in  some  insects  these  organs  are  much  more  com- 
plicated. 

In  several  genera  of  Rove-beetles  (Staphylmida)  each  mandible  is  furnished 
with  an  appendage  (Fig.  23).  This  was  named  the  prostheca  by  Kirby  and 
Spence. 


FIG.  23.— Mandible  of  Staphylinus. 


Fig.  24. — Mandible  of  Euphoria  inda. 


In  many  beetles  of  the  family  Scarabaeidae  each  mandible  consists  of  several 
more  or  less  distinct  sclentes.  This  is  wel.  shown  in  the  mandible  of  Euphoria 
inda  (Fig.  24).  These  compound  mandibles  have  not  yet  been  studied  with 
sufficient  care  to  enable  us  to  definitely  name  the  parts. 

The  M axilla. — The  maxillae  (n)  are  the  more  ventral  of  the  two  pairs  of 
jaws.  They  are  much  more  complicated  than  the  mandibles,  each  maxilla 
consisting,  when  all  of  the  parts  are  present,  of  five  primary  parts  and  three  ap- 
pendages. The  primary  parts  are  the  cardo  or  hinge,  the  stipes  or  footstalk, 
the  palpife.r  or  palpus-bearer,  the  subgalea  or  helmet-bearer,  and  the  lacinia  or 
blade.  The  appendages  are  the  maxillary  palpus  or  feeler,  \\\e  galea  or  superior 
lobe,  and  the  digitus  or  finger.  The  maxilla  may  also  bear  claw-like  or  tooth- 
like  projections,  spines,  bristles,  and  hairs. 

In  the  following  description  of  the  parts  of  the  maxillae,  only  very  general 
statements  can  be  made.  Not  only  is  there  an  infinite  variation  in  the  form  of 
these  parts,  but  the  same  part  may  have  a  very  different  outline  on  the  dorsal 
aspect  of  the  maxilla  from  what  it  has  on  the  ventral.  Compare  Fig.  25  and 
Fig.  26,  which  represent  the  two  aspects  of  the  maxilla  of  Hydrophilus.  Except- 
ing Fig.  26,  the  figures  of  maxillae  represent  the  ventral  aspect  of  this  organ. 


FIG.  25.— Ventral  aspect  of 
max  i  1  la  o  f  Hydroph  t     : 


FIG.  26. — Dorsal  aspect  of 
maxilla  of  Hydrophilus. 


FIG.  27.— Maxilla  of  Eleodes. 


The  Cdrdo  or  hinge  (a)  is  the  first  or  proximal  part  of  the  maxilla.  It  is 
usually  more  or  less  triangular  in  outline,  and  is  the  part  upon  which  nearly  all 
of  the  motions  if  this  organ  depend.  In  many  cases,  however,  it  is  not  the 


14  AN  INTRODUCTION   TO  ENTOMOLOGY. 

only  part  directly  joined  to  the  body  ;  for  frequently  muscles  extend  direct  to 
the  subgalea,  without  passing  through  the  cardo. 

The  Stipes  or  footstalk  (b)  is  the  part  next  in  order  proceeding  distad.  It  is 
usually  triangular,  and  articulates  with  the  cardo  by  its  base,  with  the  palpifer 
by  its  lateral  margin,  and  with  the  subgalea  by  its  mesal  side.  In  the  Orthop- 
tera,  Pseudoneuroptera,  and  Neuroptera,  the  stipes  is  united  with  the  subgalea, 
and  the  two  form  the  larger  portion  of  the  body  of  the  maxilla  (Fig.  22).  The 
stipes  has  no  appendages ;  but  the  palpifer  on  the  one  side,  and  the  subgalea 
on  the  other,  may  become  united  to  the  stipes  without  any  trace  of  suture 
remaining,  and  their  appendages  will  then  appear  to  be  borne  by  the  stipes. 
Thus  in  Fig.  22  it  appears  to  be  the  stipes  that  bears  the  galea,  and  that  receives 
muscles  from  the  body. 

The  Palpifer  or  palpus-bearer  (c)  is  situated  upon  the  lateral  (outer)  side  of 
the  stipes  ;  it  does  not,  however,  extend  to  the  base  of  this  organ,  and  frequently 
projects  distad  beyond  it.  It  is  often  much  more  developed  on  the  dorsal  side 
of  the  maxilla  than  on  the  ventral  (Figs.  25  and  26).  It  can  be  readily  distin- 
guished when  it  is  distinct  by  the  insertion  upon  it  of  the  appendage  which 
gives  to  it  its  name. 

The  Maxillary  Palpus  or  feeler  (d)  is  the  most  conspicuous  of  the  appendages 
of  the  maxilla.  It  is  an  organ  composed  of  from  one  to  six  freely  movable  seg- 
ments, and  is  articulated  to  the  palpifer  on  the  latero-distal  angle  of  the  body 
of  the  maxilla. 

The  Subgalea  or  helmet-bearer  (<?)  when  developed  as  a  distinct  sclerite  is 
most  easily  distinguished  as  the  one  that  bears  the  galea.  It  bounds  the  stipes 
more  or  less  completely  on  its  mesal  (inner)  side,  and  is  often  directly  connected 
with  the  body  by  muscles.  In  many  Coleoptera  it  is  closely  united  to  the 
lacinia;  this  gives  the  lacinia  the  appearance  of  bearing  the  galea,  and  of  being 
connected  with  the  body  (Fig.  28).  In  the  Orthoptera,  the  Pseudoneuroptera, 
and  the  Neuroptera,  the  subgalea  is  united  to  the  stipes ;  consequently  in  these 
orders  the  stipes  appears  to  bear  the  galea,  and  to  be  joined  directly  to  the 
body  if  any  part  besides  the  cardo  is  so  connected. 

The  Galea  or  helmet  (/)  is  the  second  in  prominence  of  the  appendages  of  the 
maxilla.  It  consists  of  one  or  two  segments,  and  is  joined  to 
the  maxilla  mesad  of  the  palpus.  The  galea  varies  greatly  in 
form  :  it  is  often  more  or  less  flattened,  with  the  distal  seg- 
ment concave,  and  overlapping  the  lacinia  like  a  hood.  It 
was  this  form  that  suggested  the  name  galea  or  helmet. 
In  other  cases  the  galea  resembles  a  palpus  in  form  (Fig. 
28).  The  galea  is  also  known  as  the  outer  lobe,  the  upper 
lobe,  or  the  superior  lobe. 

The  Lacinia  or  blade  (g)  is  borne  on   the  mesal  (inner) 
FIG.  28.-Maxiila  of  margin  of  the  subgalea.     It  is  the  cutting  or  chewing  part 
Cidndeia.          .Qf  the  maxilla,  and  is  often  furnished  with  teeth  and  spines. 
The  lacinia  is  also  known  as  the  inner  lobe,  or  the  inferior  lobe. 

The  Digitus  or  finger  (k)  is  a  small  appendage  sometimes  borne  by  the  lacinia 
at  its  distal  end.  In  the  Cicindelidse  it  is  in  the  form  of  an  articulated  claw 
(Fig.  28) ;  but  in  certain  other  beetles  it  is  more  obviously  one,  of  the  segments 
of  the  maxilla  (Figs.  25  and  26).  This  part  is  sometimes  termed  the  unguis,  a 


THE  ANATOMY  OF  INSECTS.  15 

name  applied  by  Kirby  and  Spence  to  it  and  to  the  other  claw-like  projections 
of  the  maxilla.  The  French  entomologists  distinguish  it  as  le  premaxillaire. 
Neither  of  these  names  is  desirable ;  the  former  is  not  restricted  to  this  part  of 
the  maxilla,  but  is  often  applied  to  the  terminal  portion  of  the  lacinia;  the  latter 
name  is  objectionable  both  in  form  and  signification  ;  it  is  hardly  appropriate 
to  apply  the  prefix  prce  to  the  most  distal  part  of  an  appendage.  I  propose, 
therefore,  the  name  digitus  for  this  sclerite. 

The  Ldbium  or  Second  Maxilla. — The  labium  or  under  lip  (12)  is  attached  to 
the  cephalic  border  of  the  gula,  and  is  the  most  ventral  of  the  mouth  parts.  It 
appears  to  be  a  single  organ,  although  sometimes  cleft  at  its  distal  extremity  ; 
it  is,  however,  composed  of  a  pair  of  appendages  grown  together  on  the  middle 
line  of  the  body.  In  the  Crustacea  the  parts  corresponding  to  the  labium  of 
insects  consist  of  two  distinct  organs,  very  closely  resembling  the  maxillae.  In 
this  case  they  are  termed  the  second  maxillae,  a  name  which  is  sometimes 
applied  to  the  labium  of  insects.  Hence  in  defining  the  Hexapoda  it  is  stated 
that  they  have  two  pairs  of  maxillae. 

In  naming  the  parts  of  the  labium,  entomologists 
have  usually  taken  some  form  of  it  in  which  the  two 
parts  are  completely  grown  together,  that  is,  one 
which  is  not  cleft  on  the  middle  line  (Fig.  29). 
I  will  first  describe  such  a  labium,  and  later  one 
in  whith  the  division  into  two  parts  is  carried  as 
far  as  we  find  it  in  insects. 

The  labium  is  usually  described  as  consisting  of 

.  ° .  FIG.  29.— Labium  of  Harpalus. 

three  principal  parts  and  a  pair  of  appendages.     1  he 

principal  parts  are  the  submentum,  the  mentum,  and  the  ligula  ;  the  appendages 

are  the  labial  palpi. 

The  basal  part  of  the  labium  consists  of  two  transverse  sclerites  ;  the  prox- 
imal one,  which  is  attached  to  the  cephalic  border  of  the  gula,  is  the  submen- 
tum  (a).  This  is  often  the  most  prominent  part  of  the  body  of  the  labium. 

The  Mentum  (U)  is  the  more  distal  of  the  two  primary  parts  of  the  labium. 
It  is  articulated  to  the  cephalic  border  of  the  submentum,  and  is  often  so 
slightly  developed  that  it  is  concealed  by  the  submentum.* 

The  Ltgula  (c)  includes  the  remaining  parts  of  the  labium  except  the  labial 
palpi.  It  is  a  compound  organ  ;  but  in  the  higher  insects  the  sutures  between 
the  different  sclerites  of  which  it  is  composed  are  usually  obsolete.  Three 
parts,  however,  are  commonly  distinguished  (Fig.  29),  a  central  part,  often 
greatly  prolonged,  the  glossa  (r2),  and  two  parts,  usually  small  membranous 
projections,  one  on  each  side  of  the  base  of  the  glossa,  the  paraglossce  (c*}. 

*  Unfortunately  the  term  mentum  is  applied  by  some  entomologists  to  the  submen- 
tum, and  the  true  mentum  entirely  overlooked  or  distinguished  by  a  different  name. 
This  is  the  case  in  one  of  the  most  important  works  in  the  literature  of  American  ento- 
mology, "The  Classification  of  the  Coleoptera  of  North  America,"  by  Le  Conte  and 
Horn.     The  student  in  the  use  of  this  indispensable  work  must  bear  this  change  of  names 
mind.     These  authors  have  termed  the  true  mentum  the  hypoglottis,  and  state  that   in 
•  Carabidae  the  homologous  portion  is  often  called  the  "  basal  membrane  of  the  ligula" 
(/.  c.    p.  xviii). 


1 6  AN  INTRODUCTION   TO  ENTOMOLOGY. 

Sometimes,  however,  the  paraglossae  are  large,  exceeding  the  glossa  in  size 
From  the  base  of  the  ligula  arise  a  pair  of  appendages,  the  labial  palpi  (it). 
Each  labial  palpus  consists  of  from  one  to  four  freely  movable  segments. 

In  the  form  of  the  labium  just  described,  the  correspondence  of  its  parts  to 
the  parts  of  the  maxillae  is  not  easily  seen  ;  but  this  is  much  more  evident  in 
the  labium  of  some  of  the  lower  insects,  as  for  example  a  cockroach  (Rig.  30). 
Here  the  organ  is  very  deeply  cleft ;  only  the  submentum 
and  mentum  remain  united  on  the  median  line  ;  while  the 
ligula  consists  of   two  distinct   maxilla-like  parts.     It  is 
easy   in   this  case  to  trace  the   correspondence  referred 
to  above.     Each  lateral    half  of   the  submentum  corre- 
sponds to  the  cardo  of  a  maxilla  ;  each  half  of  the  mentum, 
to  the  stipes;  while  the  remaining  parts  of  a  maxilla  are 
represented  by  each   half  of  the   ligula,  as  follows  :  near 
the  base  of  the  ligula  there  is  a  part  (c1)  which  bears  the 
FlG'  ?T~kroachm  °f         labial  palpus ;  this  appears  in  the  figure  like  a  basal  segment 
of  the  palpus  ;  but  in  many  insects  it  is  easily  seen  that  it 

is  undoubtedly  one  of  the  primary  parts  of  the  organ  ;  it  has  been  named  the 
pdlpiger,  and  is  the  homologue  of  the  palpifer  of  a  maxilla.  The  trunk  of  each 
half  of  the  ligula  is  formed  by  a  large  sclerite  (r4)  to  which  I  believe  attention 
has  not  been  called  heretofore.  This  evidently  corresponds  to  the  subgalea. 
At  the  distal  extremity  of  this  subgalea  of  the  labium  there  are  two  append- 
ages. The  lateral  one  of  these  (cs)  is  the  paraglossa,  and  obviously  corre- 
sponds to  the  galea.  The  mesal  offe  (r2)  corresponds  to  the  lacinia  or  inner 
lobe.  This  part  is  probably  wanting  in  those  insects  in  which  the  glossa  con- 
sists of  an  undivided  part ;  and  in  this  case  the  glossa  probably  represents  the 
united  and  more  or  less  elongated  subgalese. 

The  Epiphdrynx  and  the  Hypopharynx. — In  addition  to  the  mouth-parts 
described  above,  either  the  labrum  or  the  labium  may  bear  on  its  ental  surface, 
within  the  cavity  of  the  mouth,  a  more  or  less  tongue-like  organ.  If  borne  by 
the  labrum,  it  is  termed  the  epipharynx  (9) ;  if  by  the  labium,  the  hypopharynx 
(13).  (See  Fig.  22.)  The  epipharynx  and  the  hypopharynx  are  rarely  both 
developed  in  the  same  insect,  except  in  some  Hymenoptera.  The  form  and 
position  of  the  hypopharynx  are  analogous  to  those  of  the  tongue  of  higher 
animals.  On  this  account  it  has  been  named  the  lingua  or  tongue.  But  as 
both  of  these  terms  have  been  applied  to  the  glossa,  it  is  best  to  designate  this 
part  as  the  hypopharynx,  and  to  avoid  the  use  of  the  terms  lingua  and  tongue, 
as  liable  to  be  ambiguous. 

The  Thorax. 

The  thorax  is  the  second  or  intermediate  region  of  the  body.  It 
is  readily  distinguished  by  its  appendages,  which  are  three  pairs  of 
legs  and  one  or  two  pairs  of  wings.  This  region  consists  of  three 
segments.  The  cephalic  or  first  segment  is  named  the  prothorax 
(14)  ;  the  second,  the  mesothorax  (15) ;  and  the  third,  the  metathorax 
(16).  Each  segment  bears  a  pair  of  legs  ;  and  in  winged  insects  the 
wings  are  borne  by  the  second  and  third  segments. 


THE  ANATOMY  OF  INSECTS. 


The  Fixed  Parts  of  the  Thorax.* 

Each  segment  of  the  thorax  is  composed  of  several  sclerites.  The  shape 
and  relative  position  of  these  sclerites  afford  characters  which  are  much  used 
in  classification.  Fig.  31  is  a  diagrammatic  representation 
of  what  is  considered  the  typical  arrangement  of  these 
parts  in  each  of  the  thoracic  segments.  Each  segment 
of  the  thorax  is  a  ring,  which  is  divided  into  four  parts  : 
a  dorsal,  a  ventral,  and  two  lateral.  The  dorsal  part 
is  named  the  ndtum  or  tergum  ;  each  lateral  part  the 
pleurum  ;  and  the  ventral  part  the  sternum. 

When  the  notum  or  sternum  of  a   particular  thoracic 


FIG.  31.— Diagram  of  the 
fixed  parts  of  a  thoracic 
segment. 


segment  is  to  be  indicated,  it  is  done  by  the  use  of  one  of  the  prefixes  pro, 
meso,  or  meta.  In  this  way  are  formed  the  terms  pronotum,  mesonotum,  meta- 
notum,  prosternum,  mesosternum  and  metasternum  ;  which  are  applied  to  the 
notaand  sterna  of  the  prothorax,  mesothorax  and  metathorax  respectively. 

By  some  writers  the  entire  dorsal  part  of  an  insect  is  termed  the  tergum  ; 
the  lateral  part,  the  pleilrum ;  and  the  ventral  part,  the  stermtm.  These 
writers  apply  the  terms  tergite,  pleurite,  and  sternite  respectively  to  the  dorsal, 
lateral  and  ventral  regions  of  each  segment. 

The  tergum  of  each  thoracic  segment  is  composed  typically  of  four  scle- 
rites. These  are  arranged  in  a  linear  series.  They  are  named,  beginning  with 
the  first  or  most  cephalic,  prascutum  (a),  scutum  (b),  scutellum  (c),  and  postscu- 
tellum  (d).  (Fig.  32.)  In  the  prothorax  the  sutures  bemeen  these  four  scle- 


FIG.  32. — Dorsal  aspect  of  the  thorax  of  a  beetle, 
Dysticus,  dissected.     (After  Audouin.) 


FIG.  33. — Necrophorns,  to  show  scutellum. 


*  The  more  important  works  on  the  nomenclature  of  the  parts  of  the  thorax  are  the 
following  : 

Audouin,  J.  V.  Recherches  anatomiques  sur  le  thorax  des  animaux  articules  et  celui 
isectes  hexapodes  en  particulier.  Annales  des  Sciences  Naturelles,  T.  I.  (1824)'. 

The  works  of  Kirby  and  Spence,  MacLeay,  Straus-Durckheim,  Newman,  and  New- 
port  cited  on  p.  12.  The  description  of  the  anatomy  of  the  thorax  by  MacLeay  was 
republished  in  the  Ann.  des  Sci.  Nat.  t.  25  (1832). 


i8 


AN  INTRODUCTION   TO  ENTOMOLOGY. 


rites  are  in  many  cases  obsolete,  the  pronotum  appearing  to  be  composed  of  a 
single  sclerite.  In  beetles  and  bugs  the  scutellum  of  the  mesothorax  is  usually 
quite  conspicuous,  appearing  as  a  more  or  less  nearly  triangular  piece  between 
the  first  pair  of  wings  at  their  base  (Fig.  33).  Most  entomological  writers  refer 
to  this  sclerite  as  the  scutellum.  Of  the  four  sclerites  which  compose  the  ter- 
gal portion  of  each  thoracic  segment,  the  scutum  is  usually  the  largest ;  the 
scutellum  is  the  second  in  importance  ;  while  the  prsescutum  and  the  postscutel- 
lum  are  frequently  but  little  developed.  We  find  in  the  Hymenoptera  that  the 
scutum  of  the  mesothorax  is  divided  into  three  parts  by  two  longitudinal 
sutures.  The  lateral  portions  of  the  scutum  thus  separated  from  the  mesal 
part  are  termed  iht pardpsides  (i5^2). 

Each  pleurum  is  composed  of  two  sclerites,  arranged  more  or  less  obliquely. 
The  cephalo-ventral  one  is  the  episternum  (e) ;  and  the  caudo-dorsal  one  the 

\ 


FIG.  34. — Ventral  aspect  of  a  beetle,  Enchroma  gigantea.    (See  Tabular  Review,  p.  23,  for  explana- 
tion of  lettering.; 

epimeron  (f).  We  find  in  many  insects  a  third  sclerite  in  each  pleurum  of  the 
mesothorax  and  metathorax.  These  sclerites  when  present  are  situated  near 
the  base  of  the  wing,  and  articulate  with  the  dorsal  margin  of  the  episternum  \\ 
they  are  the  pardptera  (g).  In  certain  orders,  especially  Hymenoptera,  the 
parafkera  of  the  mesothorax  are  small,  corneous,  concavo-convex  scales,  whicl; 
cover  and  protect  the  bases  of  the  first  pair  of  wings.  By  many  writers  these 
paraptera  are  termed  the  tegulce,  and  by  others  the  scapula.  In  the  LepidOp. 


THE  ANATOMY  OF  INSECTS.  \g 

tera,  the  paraptera  of  the  mesothorax  are  greatly  developed.  Here  they  appear 
as  leaf-like  epaulets,  which  sometimes  cover  not  only  the  bases  of  the  wings,  but 
also  the  greater  part  of  the  mesonotum.  In  descriptive  works  on  this  order 
they  are  usually  termed  the  patdgia. 

In  the  membrane  connecting  the  head  with  the  prothorax  there  is  on  each 
side  a  pair  of  small  sclerites.  These  are  termed  \\izjugular  sclerites  (lAg). 

Each  sternum  is  composed  of  a  single  sclerite.  As  indicated  above,  the 
three  sterna  are  designated  as  the  prosternum  (14*),  mesosternum  (152),  and 
metasternum  (162)  respectively. 

In  some  beetles  the  metasternum  is  divided  into  two  unequal  portions  by  a 
suture  which  extends  transversely  a  short  distance  in  front  of  the  caudal  mar- 
gin ;  the  smaller  sclerite  which  borders  the  posterior  coxae  in  front  and  often 
passes  between  them  is  called  the  ante-coxal piece  of  the  metasternum. 

i 

The  Appendages  of  the  Thorax. 

The  appendages  of  the  thorax  are  the  organs  of  locomotion. 
They  consist  of  the  legs  and  the  wings.  Of  the  former  there  are 
three  pairs ;  of  the  latter,  never  more  than  two.  The  distribution  of 
these  appendages  has  already  been  given  (p.  16).  The  legs  are 
joined  to  the  body  near  the  lateral  borders  of  the  sterna  ;  the  wings; 
near  the  lateral  margins  of  the  terga. 

The  Legs.— Each  leg  (17)  consists  of  the  fol^i-ing-named  parts 
and  their  appendages  :  coxa,  trochanter,  femur,  tibia,  and  tarsus 
(Fig.  34). 

The  Coxa. — The  coxa  (a)  is  the  proximal  segment  of  the  leg.  It  is  the  one 
by  means  of  which  the  leg  is  articulated  to  the  body.  It  varies  much  in  form, 
but  is  usually  a  truncated  cone  or  nearly  globular.  In  some  insects  the  coxae 
of  the  third  pair  of  legs  are  more  or  less  flattened  and  immovably  attached  to 
the  metasternum  (e.g.  Carabidae).  In  such  cases  the  coxae  really  form  a  part 
of  the  body-wall,  and  are  liable  to  be  mistaken  for  primary  parts  of  the  meta- 
thorax  instead  of  the  proximal  segments  of  a  pair  of  appendages. 

In  certain  insects  there  is  a  small  sclerite  between  the  coxa  and  the  epime- 
ron.  This  is  considered  an  appendage  of  the  coxa,  and  is  called  the  trochaic 
tin  (a1).  It  is  more  often  visible  in  the  prothorax  than  in  the  other  segments?^ 

The  Trochdnter. — The  trochanter  (ti)  is  the  second  part  of  the  leg.  It  con- 
sists usual1y~oF  a  very  short,  triangular  or  quadrangular  segment,  between  the 
coxa  and  the  femur.  Sometimes  the  femur  appears  to  articulate  directly  with 
the  coxa;  and  the  trochanter  to  be  merely  an  appendage  of  the  proximal  end 
of  the  femur  (e.g.  Carabidae).  But  the  fact  is  that  in  these  insects,  although 
the  femur  may  touch  the  coxa,  it  does  not  articulate  with  it;  and  the  organs 
that  pass  from  the  cavity  of  the  coxa  to  that  of  the  femur  must  pass  through 
the  trochanter.  In  the  sub-order  Terebrantia  of  the  order  Hymenoptera  the 
trochanter  consists  of  two  segments. 

The  Femur.  —  The  femur  (c)  is  the  third  part  of  the  leg;  and  is  usually  the 
largest  part.  It  consists  of  a  single  segment. 


20  AN  INTRODUCTION   TO  ENTOMOLOGY. 

The  Tibia, — The  tibia  (d)  is  the  fourth  part  of  the  leg.  It  consists  of  a  sin- 
gle segment;  and  is  usually  a  little  more  slender  than  the  femur,  although  it 
often  equals  or  exceeds  it  in  length.  In  such  species  as  burrow  in  the  ground, 
the  distal  extremity  is  greatly  broadened  and  shaped  more  or  less  like  a  hand. 
Near  the  distal  end  of  the  tibia  there  are  in  most  insects  one  or  more  spines 
which  are  much  larger  than  the  other  hairs  and  spines  which  arm  the  leg  ;  these 
are  called  the  tibial  spines  or  tibial  spurs,  and  are  much  used  in  classification. 

The  Tarsus. — The  tarsus  \e)  is  the  fifth  and  most  distal  part  of  the  leg,  that 
which  is  popularly  called  the  foot.  It  consists  of  a  series  of  segments,  varying 
in  number  from  one  to  six.  The  most  common  number  of  segments  in  the 
tarsus  is  five.  The  distal  segment  bears  one  or  two  claws  (e1).  Sometimes 
these  claws  are  strongly  bifid  or  toothed  ;  so  that  a  tarsus  may  appear  to  bear 
four  or  even  six  claws.  The  tarsi  vary  much  in  form,  and  thus  present  charac- 
ters which  are  useful  in  classification.  Sexual  characters  are  also  frequently 
presented  by  this  part. 

On  the  ventral  surface  of  the  segments  of  the  tarsus  in  many  insects  are 
cushions  of  short  hairs  or  of  membrane,  capable  of  inflation,  or  concave  plates, 
which  act  so  as  to  produce  a  vacuum  and  thus  enable  the  insect  to  walk  on  the 
lower  surface  of  objects.  These  cushions  or  plates  are  called  pulvilli  (V2).  In 
many  insects  the  pulvillus  of  the  distal  segment  of  the  tarsus  is  a  circular  pad 
projecting  between  the  tarsal  claws.  In  nrost  descriptive  works  this  is  referred 
to  as  the  pulvillus,  even  though  the  other  pulvilli  are  well  developed.  The  pul- 
villi  are  also  called  the  onychii  by  some  writers. 

With  many  insects  (e.g.  most  Diptera)  the  distal  segment  of  the  tarsus  bears 
a  pair  of  pulvilli,  one  beneath  each  claw.  In  such  cases  there  is  frequently 
between  these  pulvilli  a  third  single  appendage  of  similar  structure;  this  is 
called  the  empodium.  In  other  insects  the  empodium  is  bristle-like  or  alto- 
gether wanting. 

The  proximal  segment  of  the  tarsus  is  designated  in  some  descriptive  works 
as  the  metatarsus. 

TJie  Wings. — The  normal  number  of  wings  is  two  pairs ;  but  in 
addition  to  the  large  order  Diptera,  there  are  many  insects  which 
have  only  a  single  pair ;  and  many  other  insects  are  wingless.  As 
already  stated,  the  first  pair  of  wings  is  articulated  to  the  Ineso- 
thorax  ;  and  the  second  pair,  to  the  metathorax.  When  but  a  single 
pair  of  wings  is  present,  it  is  almost  invariably  the  first  pair. 

Each  wing  is  a  plate-like  or  membranous  expansion  which  is  first  developed 
as  a  sac-like  projection  of  the  body-wall.*  In  the  course  of  the  formation  of 
the  wing,  the  dorsal  and  ventral  walls  of  this  sac  become  united  throughout 
the  greater  part  of  their  extent.  There  are  usually  certain  lines  along  which 
the  walls  of  this  sac  are  thickened.  The  thickenings  of  the  dorsal  and  vent.n:1 
walls  are  exactly  opposed,  and  together  constitute  the  framework  of  the  wing. 
These  thickened  lines  are  termed  the  veins  or  nerves  of  the  wings  •  rr  d  th- 

*The  gradual  formation  of  wings  can  be  easily  observed  in  insects  vfitb          .cc*.tiplei 
metamorphosis.     See  description  of  the  transformations  of  the  Acridiid**- 


THE  ANATOMY  OF  INSECTS. 


arrangement  is  described  as  the  venation  or  neuration  of  the  wing.  The  terms 
veins  and  nerves  are  both  in  general  use  ;  and  when  applied  to  the  wings  of 
insects,  have  the  same  signification.  Neither  of  them  is  good  in  this  connec- 
tion ;  but  they  are  so  firmly  established  that  it  would  not  be  well  to  try  to 
change  them.  The  former,  however;  is  the  better.  For  in  very  many  insects  a 
groove  extends  along  the  ental  surface  of  the  thickenings  of  each  wall ;  and  the 
groove  of  the  dorsal  and  ventral  thickenings  being  exactly  opposed,  form  a 
tube  in  the  centre  of  each  so-called  vein  or  nerve,  within  which  the  fluids  of" 
the  body  circulate.  In  many  insects  these  tubes,  or  veins  as  I  shall  call  them, 
are  also  traversed  by  the  air-vessels  or  tracheae. 

The  thin  spaces  circumscribed  by  the  veins  are  called  cells. 

An  insect's  wing  is  more  or  less  triangular  in  outline  ;  it  therefore  presents 
three  margins  (Fig.  35).  To  these  special  names  have  been  applied  ;  there  is 
however,  a  lack  of  uniformity  among 
entomologists  in  the  terms  which  they 
use.  The  cephalic  margin,  Fig.  35, 
1-2,  is  termed  the  front  margin,  costal 
margin,  or  simply  the  costa.  The  distal 
margin,  Fig.  35,  2-3,  is  known  as  the 
outer  margin,  or  dpical  margin.  And 
to  the  caudal  margin,  Fig.  35,  3-4,  are 
applied  the  terms  inner  margin  and 
anal  margin. 

The  angle  of  the  wing  at  the  union 
of  the  cephalic  and  distal  margins, 
Fig.  35,  2,  is  the  apex  of  the  wing ;  and 
the  angle  between  the  distal  and  cau- 
dal margins,  Fig.  35,  3,  is  the  inner 
angle.  The  proximal  end  of  the  wing  is  referred  to  as  the  base. 

With  certain  insects  (Hymenoptera  and  some  Homoptera)  the  cephalic  mar- 
gin of  the  hind  wings  bears  a  row  of  hooks,  which  fasten  into  a  corresponding 
fold  on  the  caudal  margin  of  the  front  wings.  These  hooks  are  named  the 
hdmiili,  and  serve  to  hold  the  two  wings  of  the  same  side  together,  thus  insur- 
ing their  action  as  a  unit. 

In  the  moths  the  wings  are  united  in  a  somewhat  different  way.  On  the 
lower  surface  of  the  front  wing  near  its  base  there  is  a  hook  formed  of  either  a 
portion  of  membrane  or  a  tuft  of  hairs  ;  into  this  hook  there  fits  a  bristle,  the 
frenulum,  which  springs  from  the  hind  wing  near  its  base.  The  frenulum  is 
simple  in  the  males  ;  but  it  consists  of  several  bristles  in  the  other  sex. 

The  wings  present  many  characters  which  are  much  used  in  classification. 
These  are  variations  in  texture,  form,  clothing  and  venation. 

The  most  striking  variations  in  texture  are  presented  by  the  first  pair  of 
wings.  Special  names  have  been  applied  to  the  wings  exhibiting  the  more 
important  of  these  variations.  These  are  elytra,  hemelytrc,  and  tegmina. 

Th    Elytra. — The  term  elytra  is  applied  to  the  first  pair  of  wings  of  beetles 

;.     These  wings  are  thick,  horny  or  leathery,  without  veins  or  with 

*  mer-ji^       ceo  of  them,  and  when  not  in  use  they  are  horizontal,  and  meet 


FIG.  35.— Wing  of  Hepialus. 


22  AN  INTRODUCTION   TO  ENTOMOLOGY. 

in  a  straight  line  on  the  middle  of  the  back.  The  elytra  are  also  called  wing- 
covers. 

The  Hemelytra. — This  term  is  applied  to  the  first  pair  of  wings  when  they 
are  horny  or  leathery  at  the  base  and  membranous  at  the  apex,  as  in  the  Hete- 
roptera. 

The  Tcgmina. —  This  name  is  given  to  the  mesothoracic  wings  when  they 
are  of  an  uniform  leathery  or  parchment-like  texture,  and  are  furnished  with 
veins.  Of  this  form  are  the  mesothoracic  wings  of  Orthoptera.  Like  the  ely- 
tra the  tegmina  are  also  called  wing-covers  ;  but  unlike  elytra  they  overlap  each 
other  when  at  rest. 

The  Halteres,  Balancers,  or  Poisers. — With  most  insects  that  possess  only  the 
first  pair  of  wings  (Diptera  and  the  males  of  Coccidse)  the  metathorax  is  fur- 
nished with  a  pair  of  appendages  which  are  believed  to  be  the  homologues  of 
the  second  pair  of  wings.  These  are  called  halteres,  balancers,  or  poisers.  The 
halteres  are  usually  club-shaped  or  thread-like,  terminating  in  a  knob.  In  the 
Coccidae  each  of  the  halteres  is  usually  furnished  with  a  bristle  which  is  hooked 
and  fits  into  a  pocket  on  the  wing  of  the  same  side.  In  this  case  the  halteres 
appear  to  aid  in  flight. 

The  Pseudo-halter  es. — The  insects  belonging  to  the  family  Stylopidae  have 
only  the  metathoracic  wings  developed.  The  mesothoracic  wings  are  repre- 
sented by  a  pair  of  slender  club-shaped  appendages,  which  are  termed 
pseudo  -ha  Iteres. 

Venation. — The  number  and  situation  of  the  veins  of  the  wing  afford  charac- 
ters which  are  much  used  in  descriptive  works.  The  variations  presented  by 
these  characters  are  very  great.  And  unfortunately  no  one  has  published  an 
exhaustive  work  on  the  subject.*  Much  has  been  written  upon  it;  but  most  of 
the  writers  have  confined  themselves  to  a  single  order  or  even  family  of  in- 
sects. The  result  is  that  many  systems  exist ;  and  frequently  homologous  veins 
bear  different  names  in  different  groups  of  insects.  It  is  necessary,  therefore, 
in  the  study  of  any  order  of  insects  to  learn  the  system  or  systems  that  have 
been  established  for  that  order.  The  more  important  of  these  are  explained  in 
the  discussions  of  the  orders  in  the  following  chapters  of  this  work. 

The  Abdomen. 

The  abdomen  is  the  third  or  caudal  region  of  the  body.  Its 
segments  are  more  simple,  distinct,  and.  ring-like  than  those 
of  the  other  regions.  The  number  of  segments  of  which  it  ap- 
pears to  be  composed  varies  greatly.  In  the  Cuckoo-flies  (Chrysi- 
didae)  there  are  usually  only  three  or  four  visible,  while  in  many 
other  insects  nine  appear.  Except  in  the  lowest  order  of  insects 
(Thysanura)  the  abdomen  of  the  adult  bears  no  locomotive  ap- 
pendages. But  many  larvae  have  fleshy  appendages  which  aid  in 

*  The  most  important  of  the  attempts  to  work  out  the  homologies  of  the  wing  veins  is 
by  Josef  Redtenbacher.  Ann.  des  K.  K.  Nat.  Hofmuseums,  I.  .(Wien,  1886).  See  Re- 
view in  Am.  Nat.  vol.  xxi.  p.  932. 


THE  ANATOMY  OF  INSECTS.  23 

locomotion  ;  these  are  termed  prolegs,  and  are  shed  with  the  skin 
when  the  larva  changes  to  a  pupa.  In  the  adult  the  end  of  the 
body  in  many  families  is  furnished  with  jointed  filaments,  the  ccrci, 
and  caudal  setcz.  Frequently  also  the  body  is  furnished  in  the  males 
with  organs  for  clasping,  the  claspcrs  ;  and  in  the  females  with  saws, 
piercers,  or  borers,  the  ovipositor.  In  the  females  of  certain  insects 
there  is  a  sting,  which  is  used  as  .an  organ  of  defence  ;  and  the  ab- 
domen of  plant-lice  and  certain  other  insects  bears  a  pair  of  tubes 
or  tubercles,  through  which  honey-dew  is  excreted  ;  these  are  com- 
monly called  honey-tubes  ;  they  are  also  termed  cornicles,  nectaries, 
or  sipJiuncles. 

TABULAR   REVIEW. 

The  numbers  and  letters  preceding  the  names  of  parts  are  those 
by  which  these  parts  are  designated  in  the  figures  illustrating  this 
chapter.  In  some  cases,  where  there  is  no  danger  of  mistake,  only 
the  letters  are  used  in  the  illustrations.  Thus,  in  the  figures  of 
maxillae,  the  cardo  is  indicated  by  a,  not  \\a. 

T    TT     H          j  Fixed  Parts  of  the  Head. 

/  Movable  Parts  of  the  Head. 
(  Prothorax. 
Body.-     ,I.Thora,         Mesoiho^. 


FIXED  PARTS  OF  THE  HEAD. 

1.  Occiput.  (  2a.  Front. 

2.  Epicranium.    -J  26.  Vertex. 

(  2c.  Genae. 

3.  Eyes.     (Compound  Eyes). 

4.  Ocelli.     (Simple  Eyes). 

c   Clvneus    \  $a'  Ante-clypeus. 

5.  uypeus.  ^  ^    Post.clypeus. 

6.  Gula. 

MOVABLE  PARTS  OF  THE  HEAD. 
'  B"lb" 


7«.  Scape, 

7.  Antenna.    ,  ^.  Pedice! 

.  Clavola.  \  ;<r2.   Funicle. 
/  lc\  Club. 

8.  Labrum. 

9.  Epipharynx. 

HT     j-ui     \  icvi.  Prostheca. 
10.  Mandible.  ' 


AN  INTRODUCTION   TO  ENTOMOLOGY. 


ii.  Maxilla. 


12.   Labiurn,  or 
Second  Maxillae. 


13.  Hypopharynx 


na.  Cardo. 

lib.    Stipes. 

nc.    Palpifer. 

nd.  Maxillary  Palpus. 

lie.   Subgalea. 

i  if.  Galea  (Superior  Lobe  or  Outer  Lobe). 

ng.  Lacinia  (Inferior  Lobe  or  Inner  Lobe). 

nh.  Digitus  (Unguis). 

i2a,   Submentum  (=  Cardo). 
i2b.   Mentum  (=  Stipes). 

[lie1.  Palpiger  (=  Palpifer). 

i2r2.  Glossa  (=  Subgaleae). 

I2<rs.  Paraglossa  (=  Galea). 

i2c*. (=  Subgalea). 


lie.  Ligula. 


i2d.  Labial  palpi, 


14.   Prothorax. 


15.  Mesothorax.   • 


FIXED  PARTS  OF  THE  THORAX. 


Dorsal  Surface. 
(Pronotum.) 


?.  Prsescutum. 
\    Scutum. 
'.    Scutellum. 
i.  Postscutellum. 




(Pleura.) 


Episternum. 
'.  Epimeron. 
I  r4b'-  Jugular  Sclerites. 
[  I4//.  Peritreme. 


Ventral  Surface.  ]  142.    Prosternum. 
(Sternum,) 


Dorsa.  Surface. 
(Mesonotum.) 


Lateral  Surface. 
(Pleura.) 

Ventral  Surface. 
(Sternum.) 


(  i$a.   Praescutum. 


i$c.    Scutellum. 
i^d.  Postscutellum, 

15^.    Episternum. 
i$y.  Epimeron. 
15^.  Parapteron. 
15/2.  Peritreme. 

152'.    Mesosternum. 


1 6.  Metathorax.  < 


f  1 6a.  Praescutum. 
Dorsal  Surface.    J  l^'   Scutum. 
(Metanotum.)       l6/:    Scutellum 

[  i6d.  Postscutellum. 

f  i6e.   Episternum. 
i6y.  Epimeron. 
i6g.   Parapteron. 
i6h.  Peritreme. 


Lateral  Surface, 
(Pleura.) 


Ventral  Surface.  <  i6/.  Metasternum. 
(Sternum.)          / 


Ante-coxal 
piece. 


THE  ANATOMY  OF  INSECTS. 


APPENDAGES  OF  THE  THORAX. 


17.  Leg. 


1 8.   Wings. 


19.  Pro-legs. 

20.  Cerci. 


'l7a.  Coxa.!17"''  Trochantin. 

\7b.   Trochanter. 

17^.    Femur. 

\7it.  Tibia. 

T7/,     Tqrsn  -    \  I7e*-  Claws, 
i  /€.     larsus.  <        2    T»  i   -ii' 
1                      \  ije*.  Pulvilh. 

•• 

f  Membranous. 

r         ( 

Cephalic. 

Borders.  < 

Distal. 

Elytra. 

( 

Caudal. 

Apex. 

Hemelytra. 

Angles.    < 

Inner  angle. 

i                      ^ 

Base. 

Tegmina. 

Veins.       ( 

(  A  special  nomencla- 

Cells.        \ 

/      ture  for  each  order. 

Halteres. 

Hamuli. 

Pseudo-halteres. 

Hook  and 

frenulum. 

APPENDAGES  OF  THE  ABDOMEN. 


21.  Caudal  setae. 

22.  Claspers. 

23.  Ovipositor. 


24.  Sting. 

25.  Honey-tubes. 


THE  INTERNAL  ANATOMY  OF  INSECTS. 

In  order  to  obtain  a  clear  idea  of  the  relative  positions  of  the 
different  systems  of  organs  in  the  body  of  an  insect,  let  us  recall 
the  type  of  the  Arthropoda  described  in  the  Introductory  Chapter. 
A  diagrammatic  representation  of  this  type  is  given  in  Fig.  36. 


FIG.  36.— Diagram  of  structure  of  Arthropoda. 

The  body-wall  is  a  hollow  cylinder ;  within  this  the  viscera  are 
arranged  as  follows  :  The  alimentary  canal  is  central ;  the  greater 
part  of  the  nervous  system,  ventral ;  and  the  circulatory  system, 
dorsal.  To  this  simple  conception  it  will  be  necessary  to  add  a 
complicated  respiratory  system,  not  possessed  by  the  lower  Arthro- 
pods, and  the  muscular  system  and  organs  of  reproduction,  the  dis- 
cussion of  which  was  omitted  from  the  Introductory  Chapter. 

The  Internal  Skeleton.  —  Although  the  skeleton  of  an  insect  is 
chiefly  an  external  one,  there  are  prolongations  of  it  into  the  body- 
cavity.  As  these  form  support  for  various  organs,  and  attachment 
for  many  muscles,  they  are  often  described  as  the  internal  skeleton. 


26  AN  INTRODUCTION   TO  ENTOMOLOGY. 

This  internal  skeleton  becomes  much  more  highly  developed  in 
adult  insects  than  it  is  in  larvae.  Special  names  have  been  applied  to 
the  parts  of  it  in  the  head  and  the  three  thoracic  segments.  Thus 
the  internal  skeleton  of  the  head  is  termed  the  endocrdnium  or  tento- 
rium;  and  the  principal  parts  of  it  in  the  thoracic  segments,  those 
which  project  from  the  sternal  wall,  are  distinguished  as  the  ante- 
furca,  the  vicdifurca,  and  the  postfiirca.  These  are  usually  bifurcated  ; 
they  support  the  nervous  cord  and  give  attachment  to  muscles. 

The  Minute  Structure  of  the  Body-wall. — Under  the  head  of  ex- 
ternal anatomy  the  body-wall  has  been  studied  from  one  point  of 
view.  Reference  was  there  made  to  the  hardening  of  it  by  chitine, 
and  a  special  study  was  made  of  the  various  sclerites.  We  have  now 
to  study  the  more  minute  structure  of  the  body-wall,  as  seen  on 
section  with  high  powers  of  the  microscope. 

If  a  very  thin  section  of  the  body-wall  be  taken  and  then  dyed 
with  the  proper  reagents,  so  as  to  differentiate  the  various  parts,  it 
will  be  seen  under  high  powers  of  the  microscope  to  consist  of 
three  principal  layers ;  first,  an  outer  chitinous  layer,  the  cuticle, 
which  forms  the  parts  already  studied  ;  second,  an  intermediate 
cellular  layer,  the  hypodermis ;  and  third,  a  basal  membrane. 

The  appearance  of  these  layers  is  shown  in  Fig.  37.     The  chiti- 
nous layer  is  composed  of  many  thin 
.~c         plates  superimposed.     It  really  con- 
sists of  an  excretion    of   the   inter- 
mediate  cellular   layer.     It    is    not 
composed  of   cells,  but    sometimes 
FIG.  37.-Section  of  body-wail.  it  is  marked  by  lines   correspond- 

ing to  the  outlines  of  the  subjacent  cells  of  the  hypodermis.  The 
hypodermis  is  composed  of  distinct  nucleated  cells  ;  as  it  gives 
o;-:gin  to  the  other  parts  of  the  skin,  it  is  often  termed  the  matrix. 
\  '\e  basal  membrane  is  a  thin  sheet  of  homogeneous  tissue. 

The  Muscular  System. — The  relative  positions  of  the  muscles 
and  the  skeleton  in  insects  are  very  different  from  what  they  are 
in  Man.  With  the  Vertebrates,  the  bones  constitute  a  central  axis, 
outside  of  which  the  muscles  are  arranged.  But  in  Insects,  the  skele- 
ton of  the  body,  and  of  any  of  its  appendages  as  well,  is  a  hollow 
cylinder,  to  the  ent^Lsurface  of  which  the  muscles  are  attached. 
This  is  illustrated  4|^Hg-  3$,  which  represents  the  muscles  in  the 
leg  of  a  beetle. 

If  the  body  of  an  insect  (preferably  of  a  larva)  be  opened  by  a 
longitudinal  slit,  and  the  alimentary  canal  removed  from  the  centre, 


PLATE    I. 


A  CATERPILLAK  (Cassus  ligniperda). 
(After  Lyonet.) 

Fig.  4.  Caterpillar  opened  on  the  ventral  middle  line.  Fig.  5.  Caterpillar  opened  on  the  dorsal 
middle  line,  i,  principal  longitudinal  tracheae  ;  2,  central  nervous  system  ;  3,  aorta  ;  4,  longi- 
tudinal dorsal  muscles  ;  5.  longitudinal  ventral  muscles;  6,  wings  of  the  heart ;  7,  trachea!  trunks 
arising  near  spiracles  ;  8,  reproductive  organs;  9,  vertical  muscles;  10,  last  abdominal  spiracle. 


28  AN  INTRODUCTION   TO  ENTOMOLOGY. 

a  large  part  of  the  muscular  system  will  be  exposed  to  view.  Plate 
I.  represents  the  thorax  and  abdomen  of  a  larva  which  has  been  pre- 
pared in  this  way.  In  these  figures  the  band-like  structures  repre- 
sented as  lining  the  body-wall  are  muscles.  And  the  number  is  much 
greater  than  shown  here  ;  for  between  these  muscles  and  the  body- 
wall  there  are  in  most  places  several  layers  of  diagonal  muscles. 

The  muscular  system  is  composed  of  an  immense  number  of  dis- 
tinct, isolated,  straight  fibres,  which  are  always  free  (i.e.,  not  inclosed 
in  tendinous  sheaths  as  with  Vertebrates).  As  a  rule,  the  muscles 
that  move  the  segments  of  the  body  are  not  furnished  with  tendons 
(Plate  I.) ;  while  those  that  move  the  appendages  are  thus  united  at 
the  distal  end  (Fig.  38).  In  appearance  the  muscles  are  either 


FIG.  38.— Leg  of  May-beetle.    (After  Straus-Durckheim.) 

colorless  and  transparent,  or  yellowish-white  ;  and  of  a  soft,  almost 
gelatinous  consistence.  When  properly  treated  with  histological 
reagents,  and  examined  with  a  microscope  of  moderately,  high 
power,  they  present  numerous  transverse  striations,  like  the  volun- 
tary muscles  of  Vertebrates. 

The  Alimentary  Canal. — In  the  ideal  figure  given  on  page  25,  the 
alimentary  canal  is  represented  as  a  straight  tube  extending  from 
one  end  of  the  body  to  the  other.  In  the  larva  of  some  insects  there 
is  an  approach  to  this  degree  of  simplicity.  But  usually  the  tube  is 
longer  than  the  body,  and  is  consequently  more  or  less  convoluted. 
Moreover,  it  is  not  of  uniform  structure,  but,  as  in  the  higher  animals, 
different  parts  are  adapted  to  different  functions.  Names  have 
been  applied  to  these  special  parts  similar  to  those  used  to  desig- 
nate the  analogous  parts  in  higher  animals.  These  are  as  follows  : 

There  is  within  the  head  a  portion  of  the  alimentary  canal  that 
is  usually  more  or  less  enlarged  ;  this  is  the  pharynx.  It  has  been 
shown  recently  *  that  in  some  sucking  insects  the  pharynx  is  fur- 
nished with  powerful  muscles,  by  which  it  can  be  distended,  and 
that  it  is  doubtless  the  pumping  organ,  by  which  these  insects 

*  Edward  Burgess,  Contributions  to  the  Anatomy  of  the  Milkweed  Butterfly  (Me- 
moirs of  the  Boston  Society  of  Natural  History,  1880). 

George  Dimmock,  The  Anatomy  of  the  Mouth-parts  and  Sucking  Apparatus  of  some 
Diptera  (Boston,  1881). 


PLATE  II. 


A  COCKROACH  (Periplaneta  orientalis). 
(From  Rolleston.) 

antennae  ;  <5r,  £2,  £3,  tibiae  ;  c,  anal  cerci ;  d,  ganglion  on  recurrent  nerve  upon  the  crop  ;  r,  salivary 
duct ;  y,  salivary  bladder  ;  g,  gizzard  ;  A,  hepatic  cosca  ;  /,  chylific  stomach  ;  j\  Malpighian 
vessels  :  k,  small  intestine;  /,  large  intestine  ;  w,  rectum  ;  «,  first  abdominal  ganglion;  o,  ovary; 
/,  sebaceous  glands. 


3O  AN  INTRODUCTION   TO  ENTOMOLOGY. 

obtain  their  food.     We  do  not  know  yet  how  generally  this  is  true 

of  sucking  insects. 

Following  the  pharynx  and  extending  into  or  through  the  thorax 

is  a  slender  part,  the  (esophagus. 

In  many  insects,  both  sucking  and  biting,  there  is  a  dilation  of 

the  oesophagus  near  its  caudal  end,  which  serves  as  a  reservoir  of  food, 

and  is  termed  the  crop.     The  crop  of  sucking  insects  was   formerly 

thought  to  be  the  pumping  organ,  and  is,  therefore,  described  in  the 

older  works  on  this  subject  as  the  sucking  stomach. 

Following  the  crop  we  find  in  some  insects 
a  compact  enlargement  of  the  alimentary  canal 
with  strong  muscular  walls,  the  proventriculus 
or  gizzard.  This  is  sometimes  a  very  com- 
plicated organ,  furnished  with  teeth,  spines, 
and  hairs,  for  the  grinding  of  the  food.  (Fig. 

FIG.  3g.— Cross-section    of 
the     proventriculus      of        3Q.) 
Corydalus.  nH  7     •  ,     •  j  j    •  M 

The  stomach  is  next  in  order,  and  is  easily 

recognized  by  its  central  position,  and  usually  by  its  large  size. 
It  is  also  known  as  the  ventriculus,  or  chylific  ventricle. 

The  remaining  part  of  the  alimentary  canal  is  the  intestine.  This 
is  often  composed  of  three  specialized  regions,  named,  as  in  the 
higher  animals,  the  lleum  or  small  intestine,  the  colon  or  large  intes- 
tine, and  the  rectum. 

There  may  be  several  sets  of  appendages  to  the  alimentary 
canal.  The  first  of  these  are  the  salivary  glands,  which  open  near 
the  mouth.  These  glands  vary  greatly  in  form  and  number,  and 
are  sometimes  wanting.  In  Lepidopterous  larvae  they  constitute 
the  silk  glands,  and,  in  this  case,  have  a  distinct  opening  through  the 
modified  labium  or  "  spinneret."  At  the  beginning  of  the  stomach, 
there  are  in  many  insects  several  pouch-like  appendages,  the  ccecal 
tubes.  These  secrete  a  digestive  fluid,  which  resembles  the  pancre- 
atic, juice  of  Vertebrates.  Usually  the  most  conspicuous  of  tjie 
appendages  of  the  alimentary  canal  are  certain  long,  slender  tubes 
opening  into  the  beginning  of  the  small  intestine,  and  floating  free 
in  the  body-cavity  or  lying  upon  the  surface  of  the  stomach.  These 
are  named  the  Malpighian  vessels,  in  honor  of  Malpighi,  an  anato- 
mist who  wrote  more  than  two  hundred  years  ago.  Formerly  they 
were  supposed  to  be  biliary  vessels  ;  but  their  function  has  been 
determined  to  be  urinary.  There  are  other  glandular  appendages, 
which,  as  they  open  into  the  alimentary  canal  near  its  caudal  open- 
ing, are  termed  anal  glands.  These  probably  do  not  constitute  a 


THE  ANATOMY  OF  INSECTS. 


part  of  the  digestive  system,  but  are  organs  of  offence,  the  secretion 
being  acrid  or  otherwise  offensive. 

Insects  take  the  greater  part  of  their  food  during  the  larva  or 
nymph  state  ;  for  it  is  in  this  period  that  they  acquire  their  growth. 
In  some  cases,  as  with  the  May-flies  arid  the  Bombycid  moths,  no 
nourishment  is  taken  during  the  adult  state.  With  certain  larvae 
(larvae  of  the  higher  Hymenoptera,  Pupipara,  and  Ant-lions),  the 
stomach  ends  blindly,  and  does  not  communicate  with  the  intestine. 
In  the  Ant-lions  the  rectum  is  transformed  into  a  silk  gland ;  and 
the  silk  of  which  the  cocoon  is  made  is  spun  from  the  anus. 

The  Adipose  Tissue. — On  opening  the  body  of  an  insect,  especially 
of  a  larva,  one  of  the  most  conspicuous  things  to  be  seen  is  fatty 
tissue  in  large  masses.  These  often  completely  surround  the  ali- 
mentary canal,  and  are  held  in  place  by  numerous  branches  of  the 
tracheae  with  which  they  are  supplied.  Other  and  smaller  masses 
of  this  tissue  adhere  to  the  inner  face  of  the  abdominal  wall,  in  the 
vicinity  of  the  nervous  system,  and  at  the  sides  of  the  body.  It  also 
abounds  in  the  pericardial  sinus.  In  a  full- 
grown  larva  of  Corydalus  cornutus  I  have 
found  the  adipose  tissue  to  be  greater  in  bulk 
than  all  of  the  other  organs  found  inside  of 
the  muscular  walls  of  the' body.  In  adult  in- 
sects it  usually  exists  in  much  less  quantity 
than  in  larvae. 

The  Circulatory  System.  —  In  insects  the 
circulatory  system  is  not  a  closed  one,  the  blood 
flowing  in"  vessels  during  only  a  part  of  its 
course.  The  greater  part  of  the  circulation 
of  this  fluid  takes  place  in  the  cavities  of  the 
body  and  its  appendages,  where  the  blood 
fills  the  space  not  occupied  by  the  internal 
organs.  The  only  blood-vessels  that  exist  in 
these  animals  lie  just  beneath  the  body-wall, 
above  the  alimentary  canal  (Fig.  36,  //).  They 
extend  from  near  the  caudal  end  of  the  ab- 
domen through  the  thorax  into  the  head. 
That  part  of  this  system  that  lies  in  the  ab- 
domen is  usually  termed  the  heart,  and  con- 
sists of  a  series  of  chambers  corresponding  to 
the  segments  of  the  body  (Fig.  40,  d).  The 
number  of  these  chambers  varies,  but  it  is  rarely  more  than  eight. 


Fig.  40.— Heart  of  May-beetle 
(af  ter  S  traus-  D  u  re  khe  i  m ).  a , 
lateral  aspect  of  aorta;  £, 
interior  of  heart  showing 
valves;  c,  ventral  aspect  of 
heart  and  wing-muscles — the 
muscles  are  represented  as 
cut  away  from  the  caudal 
part  of  the  heart;  </,  dorsal 
aspect  of  heart. 


32  AN  INTRODUCTION   TO  ENTOMOLOGY. 

Miall  and  Denny,  however,  describe  the  heart  of  a  cockroach  as 
consisting  of  thirteen  chambers,  corresponding  to  ten  abdominal  and 
three  thoracic  segments.  The  chambers  of  the  heart  are  separated 
by  valves,  which  permit  the  blood  to  flow  only  towards  the  head. 
There  is  in  the  walls  of  the  heart  a  pair  of  lateral  openings  corre- 
sponding to  each  chamber ;  these  also  are  furnished  with  valves, 
which  admit  the  blood  to  the  heart,  but  prevent  its  exit.  When, 
therefore,  the  chambers  contract,  a  stream  of  blood  is  forced  towards 
the  head ;  and  when  they  expand,  the  blood  rushes  into  them 
through  the  lateral  openings. 

The  circulatory  system  has  been  carefully  studied  in  only  a  few 
insects ;  and  these  show  a  remarkable  variation   in  the  form  and 
arrangement  of  the  openings  and  valves.*    But  the  result 
of  their  operation  is  the  same  in  all.     A  diagram  of  a  hori- 
zontal section  of  the  heart  of  a  May-beetle,  based  on  the 
description    by    Straus- Durckheim    (Graber    represents 
it    as    more    complicated)  will  serve  as   an    illustration. 
Fig.  41,  S,  represents  a  chamber  of    the   heart    during 
its    systole    or    contraction ;   the  valves   at    the    caudal 
FIG.  4i.— Dia-  end  and  at  the  lateral  openings  (i)  have  been 
hear\  of  closed  by  the  pressure  of  the  blood;  while  the 

May-beetle.          ,  ,  ,      ..  , 

valves  at  the  cephalic  end  have  been  forced 
open,  and  the  blood,  represented  by  the  arrow,  is  flowing 
forwards.  D  repTesents  a  chamber  regaining  its  natural 
size,  and  the  blood  flowing  into  it  through  the  lateral 
openings. 

I  have  observed  a  somewhat  different  arrangement  of 
openings  and  valves  in  the  nymph  of  a  dragon-fly.  A 
young  individual  was  studied,  one  in  which  the  skin  was 
sufficiently  transparent  to  allow  the  beating  of  the  heart 
to  be  seen  through  it.  In  this  insect  the  most  active 
part  of  the  heart  appeared  to  be  the  caudal  chamber, 
which  is  represented  in  Fig.  42,  a.  This. chamber  was  in 
constant  motion,  expanding  and  contracting  in  rapid  suc- 
cession. With  each  expansion  the  valves  at  I  quickly  closed  and 
the  blood  rushed  in  at  2 ;  and  when  the  chamber  contracted,  the 
valves  at  2  closed  and  the  blood  was  forced  forwards  through  I. 

*  See  Dr.  V.  Graber,  Ueber  den  propulsatorischen  Apparat  der  Insecten,  Archiv  fUr 
mikroscopische  Anatomic,  Band  IX.  (1873). 
Straus-Durckheim,  Animaux  Articules  (1828). 
Miall  and  Denny,  The  Cockroach  (1886). 


THE  ANATOMY  OF  INSECTS.  33 

In  many  insects,  instead  of  a  rapid  alternation  of  contraction  and 
expansion  of  the  chambers,  the  heart  begins  to  contract  at  its  caudal 
end,  and  a  wave  of  contraction  passes  towards  the  head  along  the 
entire  length  of  the  organ  ;  frequently  one  wave  will  pass  the  entire 
length  of  the  heart  before  another  begins. 

The  cephalic  prolongation  of  the  heart,  which  extends  through 
the  thorax  and  into  the  head,  is  a  simple  tube,  the  aorta  (Plate  I., 
3  ;  Fig.  40,  c  and  a).  The  aorta  ends  in  the  head,  near  the  brain, 
where  it  is  usually  somewhat  branched.  The  branches  are  very 
shorthand  the  blood  passes  from  them  directly  into  the  body-cavity. 
Here  it  bathes  the  viscera,  receiving  the  products  of  digestion  from 
the  alimentary  canal,  giving  up  to  the  various  glands  their  secretions, 
and  carrying  nourishment  to  all  parts  of  the  body.  In  its  course 
through  the  body  the  blood  flows  in  regular  channels,  without  walls, 
like  the  currents  of  the  ocean. 

The  blood  is  usually  colorless,  or  slightly  tinged  with  green  ;  but 
its  circulation  is  made  conspicuous  by  the  movements  of  the  large 
corpuscles  with  which  it  abounds.  In  transparent  insects  it  can  be 
seen  pouring  forth  from  the  cephalic  end  of  the  aorta,  bathing  first 
the  brain,  and  then  passing  to  all  parts  of  the  body,  even  out  into 
the  appendages.  By  tracing  the  course  of  any  one  of  these  currents 
it  will  be  found  to  flow  sooner  or  later  to  the  sinus  in  which  the 
heart  rests,  and  from  which  it  receives  its  blood. 

The  Pericdrdial  Sinus,  to  which  reference  has  just  been  made,  is 
separated  from  the  general  cavity  of  the  body  by  a  membrane,  the 
pericardial  diaphragm.  This  diaphragm  is  perforated  by  many  open- 
ings, through  which  the  blood  passes  on  its  return  to  the  heart. 
Into  the  diaphragm  there  are  inserted  a  double  series  of  triangular 
muscles  (Plate  I.,  6 ;  and  Fig.  40,  c).  These  meet  on  the  mid- 
dle line,  and  are  attached  by  their  smaller  ends  to  the  lateral  walls 
of  the  body.  They  were  formerly  supposed  to  be  attached  to  the 
sides  of  the  heart,  and  to  aid  in  the  expansion  of  that  organ  ;  they 
were,  therefore,  named  by  Lyonet  the  wings  of  the  heart. 
The  relation  of  these  muscles  to  the  heart  is  shown  in 
Fig.  43,  which  is  a  diagram  of  a  cross-section  of  the  body.  \^ 
In  this  w  represents  the  position  of  the  wings  of  the  heart.  FlG.  43._Dia- 
I  do  not  think  that  the  use  of  these  muscles  has  yet  been  wfngrofthe 
fully  determined.  One  function,  though  probably  a 
subordinate  one,  is  doubtless  to  protect  the  heart  from  pressure. 
One  has  only  to  watch  the  peristaltic  movements  of  the  alimentary 
canal  in  a  transparent  larva  to  appreciate  the  importance  of  this. 


34 


AN  INTRODUCTION   TO  ENTOMOLOGY. 


The  Nervous  System. — The  central  part  of  the  nervous  system,  as 
already  indicated,  consists  of  a  ganglion  in  the  head  above  the  oesoph- 
agus, and  of  a  series  of  ganglia  (typically  one  for  each  segment  of 
the  body)  lying  on  the  floor  of  the  body-cavity,  and  connected  by 
two  longitudinal  cords.  In  the  head,  one  of  these  cords  passes  on 
each  side  of  the  oesophagus,  from  the  brain  to  another  ganglion  in 
the  head  below  the  oesophagus,  thus  forming  a  nervous  collar  about 
the  alimentary  canal.  From  each  ganglion  nerves  arise,  which  sup- 
ply the  adjacent  parts ;  and  from  the  thoracic  ganglia  nerves  extend 
to  the  legs  and  wings.  This  series  of  ganglia  is  really  a  double  one ; 
but  each  pair  of  ganglia  are  more  or  less  closely  united  on  the  mid- 
dle line  of  the  body,  and  often  appear  as  a  sin- 
gle ganglion.  Fig.  44  gives  a  general  view  of 
the  nervous  system  of  Corydalus  cornutus  as 
represented  by  Leidy.  From  the  brain  (a)  two 
large  nerves  extend  to  the  compound  eyes, 
and  a  smaller  pair  to  the  antennae ;  the  sub- 
cesophageal  ganglion  (b)  supplies  the  mouth- 
parts  with  nerves ;  and  each  of  the  thoracic 
and  abdominal  ganglia  supplies  its  segment  of 
the  body. 

In  Corydalus  (Fig,  44)  the  eighth  and  ninth 
pairs  of  abdominal  ganglia  are  united,  and 
drawn  cephalad  into  the  seventh  abdominal 
segment.  The  same  thing  is  presented  by 
the  larva  of  Cossus  (Plate  I.,  10).  This  is  an 
illustration  of  what  has  been  termed  ceph- 
alization  of  the  nervous  system.  In  the  adults 
of  insects  of  the  higher  orders  this  cephaliza- 
tion  of  the  nervous  system  is  carried  to  a 
great  extent.  In  some  cases  the  abdomjnal 
ganglia  are  fused  into  a  common  mass  and  drawn  cephalad  into  the 
thorax.  Between  this  and  the  form  presented  by  Corydalus  every 
gradation  exists.  With  the  higher  insects  the  nervous  system  un- 
dergoes marked  changes  during  the  life  of  the  individual.  In  a 
caterpillar  it  is  of  the  form  shown  in  Plate  I.;  in  the  pupa  state 
it  becomes  somewhat  shortened  ;  and  in  the  adult  the  abdominal 
ganglia  are  all  or  nearly  all  united  with  the  thoracic  ganglia  into  a 
common  nervous  mass.* 


FIG.  44.— Nervous  system  of 
Corydalus. 


*  See  figures  by  Newport,  Cycl.  Anat.  and  Phys.  II.  pp.  963-965. 


THE  ANATOMY  OF  INSECTS.  35 

In  addition  to  the  central  nervous  system  described  above,  there 
is  what  has  been  termed  the  visceral  nervous  system.  This  consists 
of  two  parts, — the  oesophagcal  nerves,  and  the  respiratory  nerves. 

There  are  two  sets  of  oesophageal  nerves, — the  unpaired  and  the 
paired.  From  each  of  the  nerve-cords  that  connect  the  brain  with 
the  subcesophageal  ganglion  there  arises  a  nerve,  which  extends 
cephalad  upon  the  oesophagus;  these  unite  to  form  the  frontal 
ganglion  (Fig.  44,  c)*  From  this  ganglion  a  recurrent  nerve  passes 
caudad  through  the  oesophageal  collar  between  the  aorta  and  the 
oesophagus.  A  short  distance  caudad  of  the  brain,  this  nerve,  in 
some  insects,  enters  a  small  ganglion,  from  which  branches  extend 
to  the  sides  of  the  alimentary  canal ;  in  other  insects  it  forms  a 
number  of  plexuses  in  the  muscular  layer  of  that  organ  without 
apparent  ganglia.  These  ganglia  and  nerves  comprise  the  unpaired 
system.  The  paired  cesophageal  nerves  arise  on  either  side  from 
the  caudal  aspect  of  the  brain,  and  swell  out  at  the  sides  of  the 
oesophagus  to  form  ganglia  (Fig.  44,  d)  which  also  supply  nerves 
to  the  walls  of  the  alimentary  canal. 

The  respiratory  nerves  are  not  represented  in  the  figure  of  Cory- 
dalus  ;  but  they  are  well  shown  in  that  of  the  larva  of  Cossus  (Plate 
I.).  They  consist  of  the  following  parts:  In  each  segment  of  the 
thorax  and  abdomen  there  is  a  short  longitudinal  cord  between  the 
two  cords  of  the  central  nervous  system.  Each  of  these  cords  en- 
larges into  a  ganglion,  from  which  branches  extend  laterally  to  the 
sides  of  the  body,  where  they  supply  the  tracheal  trunks  and  the 
muscles  of  the  spiracles. 

The  Organs  of  Special  Sense. — It  is  probable  that  insects  possess 
the  five  senses  known  to  us ;  and  perhaps  they  have  others  the  na- 
ture of  which  we  cannot  conceive.  Even  in  the  case  of  the  five 
senses,  the  range  of  perception  may  be  very  different  from  ours. 
Thus  Lubbock  has  shown  that  ants  perceive  the  ultra-violet  rays, 
which  are  invisible  to  us.  There  is,  however,  a  great  variation  in 
the  degree  of  development  of  the  different  senses  in  different  in- 
sects ;  for  example,  some  are  furnished  with  wonderful  eyes,  while 
others  are  blind.  It  is  probable  that  in  many  cases  the  great  devel- 
opment of  one  sense  is  correlated  with  a  slight  development  of  some 
other.  As  an  illustration,  we  find  that  in  the  Dragon-flies  and  Ci- 
cadas, which  are  essentially  directed  by  sight,  the  antennae  are  rudi- 

*  See  William  C.  A'rauss,  On  the  Nervous  System  of  the  Head  of  the  Larva  of  Co- 
rydalus  cornutus  :  an  extract  from  a  thesis  in  Entomology  presented  to  the  faculty  of 
Cornell  University  for  the  Baccalaureate  in  Science:  Psyche,  vol.  IV.  pp.  170-184. 


30  AN  INTRODUCTION   TO  ENTOMOLOGY. 

mentary,  and  doubtless  the  sense  of  smell  likewise.  During  the 
night  these  insects  are  passive,  while  during  the  day  they  trust  to 
their  powers  of  sight,  or  possibly  in  some  Cicadas  also  to  hearing. 

The  study  of  the  sensations  of  insects  is  at  the  same  time  one  of 
the  most  difficult  and  one  of  the  most  interesting  of  the  departments 
of  entomology.     But  as  yet  comparatively  little  has 
been  done  in  this  line.     The  great  improvements  that 
•    have  recently  been  made  in  the  methods  of  histologic- 
al  research  have  resulted  in  the  publication  of  several 
very  important  papers  on  the  structure  of  sense-organs  ; 
but  there  is  a  great  lack  of  experimental  basis  for  con- 
clusions as  to  the  functions  of  the  various  organs  that 
have  been  described.* 

The  best  known  of  the  organs  of  special  sense  are 
the  organs  of  sight.  Of  these  there  are  two  kinds, 
the  simple  eyes  and  the  compound  eyes.  Simple 
eyes  exist  in  both  larvae  and  adult  insects.  In  the 
former  there  may  be  several  of  these,  on  each  side  of 
the  head ;  in  the  latter  there  are  usually  not  more 
than  three,  situated  between  the  compound  eyes. 
The  compound  eyes  occur  only  in  adult  insects,  where 
they  reach  a  marvellous  degree  of  complexity.  Each 
compound  eye  consists  of  many  ocelli  united ;  the 
number  varies  from  50  in  some  ants  to  more  than 
30,000  in  certain  butterflies.  The  complexity  of  these 
FIG.  45.  —  Three  eyes  does  not,  however,  consist  merely  of  the  great 

ocelli  with  retinu-  ,  r  n.     .-,  .  .,  .    .  r 

la  from  the  com-  number  of  ocelli  that  enter  into  the  composition  of 
May-beeetTI.(Afte^  each ;  but  each  ocellus  is  a  highly   developed  organ 

Grenacher.)    The  .      .  ,  ~,  r    f 

pigment  has  been  consistingot  many  parts.    1  he  structure  or  these  ocelli 

dissolved      away  .  .         .          ..rf  .  „>. 

from  two  of  them,  vanes  greatly  in   aiiierent   insects. t      risf.   4^    repre- 

f,   corneal   facet;  *         „. 

K,      crystalline  sents   three    ocelli    of  a   May-beetle   as   described  by 

cone;  /,  pigment- 

sheath;  p,  chief  Grenacher, 

pigment-cell;  /",  . 

pigment -cells  of         With  regard   to  the  organs  of  special  sense  other 

the  second  order;  ** 

R,  retinuiae.  than  those  of  sight  there  is  much  doubt.  It  is  prob- 
able that  many  insects  possess  organs  of  hearing ;  for  elaborate 
sound-producing  organs  are  common  among  them.  But  the  only 

*  For  a  general  discussion  of  this  subject,  and  for  many  references  to  the  literature, 
see  Experiences  et  Remarques  critique  sur  les  Sensations  des  Inseftes,  par  Augttste  For  el, 
Recueil  Zoologique  Suisse,  t.  IV.  (1886). 

f  See  B.  T.  Lowne,  On  the  Modifications  of  the  Simple  and  Compound  Eyes  of  In- 
sects (Philos.  Trans.  1878);  also  the  works  cited  by  this  author. 


NIVER8IT 

37 


THE  ANATOMY   OF  INSECTS. 

organs  of  insects  that  are  generally  believed  to  be  ears  are  the 
so-called  tympanal  organs  of  Orthoptera,  which  are  placed  at  the 
sides  of  the  first  abdominal  segment  in  the  Acrididae,  and  near  the 
proximal  end  of  the  tibiae  of  the  first  pair  of  legs  in  the  Locustidae 
and  Gryllidae ;  and  even  in  the  case  of  these  it  is  not  proven  that 
they  have  the  function  of  hearing. 

As  to  the  sense  of  smell  many  conflicting  views  are  held  ;*  but 
the  weight  of  opinion  now  is  that  certain  antennal  structures  are  the 
organs  of  smell.  These  structures  are  to  be  found  in  the  antennae 
of  many  insects.  If,  for  example,  the  surface  of  the  plates  that  com- 
pose the  club  of  the  antennae  of  a  May-beetle  be  examined  it  will 
be  found  to  be  thickly  studded  with  pits.  These  can  be  seen  with  a 


FIG.  46. — Organ  of  smell  of 
Caloptenus.  (After  Hau- 
ser.) 


Fig.  47.— Organ  of  smell  of         Fig.  48.— Organ  of  Smell  of 
May-beetle.    (After    Hau-  Vespa.    (After  Hauser.) 


Lett 


forming  cell:  »,  nerve  of  special  sense;  nc.  nucleus  of  the  sense-  or  ganglion-cell ;  o,  opening  into 
the  olfactory  pit;  /,  olfactory  pit;  pw,  wall  of  the  pit;  sc,  sense-  or  ganglion-cell;  st,  olfactory  or 
sense-style,  sometimes  peg-shaped. 

microscope  of  low  power;  but  in  order  to  determine  the  minute 
structure  of  the  organs  thin  sections  of  them  must  be  made  and  ex- 
amined with  high  powers.  Fig.  47  represents  a  section  of  one  of 
these  pits ;  and  Figs.  46  and  48  represent  the  corresponding  organs 
in  a  locust  and  in  a  wasp.f  The  form  of  these  organs  of  smell  varies 

*  See  Packard's  abstract  of  a  paper  upon  this  subject  by  Dr.  K.  Kraepelin,  American 
Naturalist,  1886,  pp.  889  and  973. 

f  See  Hauser,  On  the  Organs  of  Smell  in  Insects,  translated  by  Packard,  American 
Naturalist,  1887,  p.  279. 


AN  INTRODUCTION   TO  ENTOMOLOGY. 


greatly   in    different    insects,    as   is   shown   by  the    accompanying 
figures.* 

What  are  supposed  to  be  organs  of  taste  in  Hymenoptera  and 
Diptera  have  been  carefully  described  by  Will.$  These  consist  of 
pits  on  the  labium  and  on  the  lower  side  of  the  maxillae  through 


FIG. 


49.— Organ  of  taste  in  the  labium 
of  Vespa  vulgaris.     (After  Will.) 


FIG.  50. — Similar  organ  in  maxilla  of  the 
same  insect.    (After  Will.) 


Lettering  of  Figs.  49  and  50.— C,  cuticle;  P,  pit  in  the  same;  Sc,  sense-cell;  Ne,  neurilemma  of  sense- 
cell;  Ac,  axis  cylinder  of  sense-cell;  E,  end  of  the  same;  N,  nerve  connected  with  sense-cell;  M, 
matrix-cells;  Gc,  gland-cells. 

which  ends  of  nerves  come  to  the  surface.     The  structure  of  these 
organs  in  Vespa  vulgaris  is  shown  in  Figs.  49  and  50. 

It  is  probable  \hz\.' organs  of 
touch  are  well  developed  in  many 
insects.  Leydig,  Hicks,  and  Vial- 
lanes  have  described  tactile  hairs, 
which  are  situated  upon  pores  in 
the  cuticle,  in  which  nerves  end. 
Figure  51  is  a  diagram  of  one  of 
these  hairs. 

The  Respiratory  System. — If  an 
insect  be  carefully  examined  there 
can  be  found  along  the  sides  of  the 
body  a  series  of  openings.  These  can  be  easily  seen  in  many  cater- 
pillars and  other  larvae;  they  are  the  openings  of  the  respiratory  sys- 
tem, and  are  termed  the  spiracles. 

The  number  of  spiracles  varies  greatly  in  different  insects. 
There  is,  however,  never  more  than  one  pair  on  a  single  segment  of 
the  body.  They  do  not  occur  on  the  head,  but  are  borne  by  each 
of  the  thoracic  segments,  and  by  the  first  eight  abdominal  segments. 
Thus  there  are  eleven  segments  that  may  bear  spiracles ;  but  they 
are  always  lacking  on  some  one  or  more  of  these. 

*  For  generalizations  regarding  these  organs  see  Kraepelin,  translated  by  Packard, 
American  Naturalist,  1887,  p.  182. 

\  Will,  F.  Das  Geschmacksorgan  der  Insekten.  Zeitschrift  fiir  Wissen.  Zool. 
1885,  p.  674. 


FIG.  51.— Diagram  of  tactile  hair,  c,  cuticle 
hy,  hypodermis;  bm,  basal  membrane;  h 
hair;  he,  hair-cell;  «,  nerve;  nc,  nerve-cell. 


THE  ANATOMY   OF  INSECTS. 


39 


These  spiracles  are  either  simple  openings  into  the  respiratory 
system,  or  are  provided  with  valves,  sieves,  or  fringes  of  hair  for  the 
exclusion  of  dirt.  They  lead  into  a  system  of  air-tubes  termed  trd- 
chece.  The  accompanying  figures  will  indicate  the  distribution  of 
the  main  trunks  of  these  tracheae  in  a  cockroach.  There  is  a  short 
trunk  arising  from  each  spiracle  ;  these  are  all  connected  together 
by  a  large  longitudinal  trunk  on  each  side  of  the  body,  and  by 
numerous  transverse  trunks.  From  these  large  tracheae  there  arise 
a  great  number  of  smaller  ones,  not  shown  in  the  figures,  which 
branch  and  subdivide,  and  extend  to  all  parts  of  the  body.  When 
one  dissects  an  insect  the  viscera  are  found  to  be  connected  together 
by  the  ramifications  of  these  tracheae,  so  that  in  order  to  remove 
any  organ  it  is  necessary  to  cut  some  of  them.  The  smaller 
branches  of  the  tracheae  are  exceedingly  minute,  and  are  intimately 


FIG.  52. — Tracheal  system  of  Cock- 
roach. The  dorsal  integument  re- 
moved and  the  alimentary  canal 
in  place.  (After  Miall  and  Denny.) 


FIG.  53. — Tracheal  system  of  Cock- 
roach. The  alimentary  canal  re- 
moved to  show  the  ventral  tra- 
cheal  communications.  (After 
Miall  and  Denny.) 


associated  with  the  various  tissues.  By  means  of  these  fine  tracheal 
trunks  the  air  is  carried  to  the  various  tissues;  so  that  they  are  sup- 
plied with  oxygen  directly  from  the  air,  without  the  intervention  of 
blood  as  in  the  higher  animals. 

The  minute  structure  of  the  tracheae  has  been  the  source  of 
much  discussion.  But  at  last  it  seems  to  be  well  understood.  The 
walls  of  the  tracheae  are  composed  of  three  layers,  which  correspond 
to  the  layers  of  the  body-wall.  In  fact  the  tracheae  are  looked  upon 
as  invaginations  of  the  body-wall.  The  continuity  of  the  mem- 
branes of  the  tracheae  and  body-wall  is  shown  diagrammatically  in 
Fig.  54.  It  should  be  observed  that  it  is  the  inner  layer  of  the  wall 
of  the  trachea  that  corresponds  with  the  outer  layer  of  the  wall  of  the 


AN  INTRODUCTION   TO  ENTOMOLOGY. 


body-wall,    c,  cuticle;  hy,  hypoder- 
mis;  \bm,  basal  membrane;  sf,  spiral 


body.  This  inner  layer  of  the  wall  of  the  trachea,  the  intima,  like  the 
cuticle  is  chitinous,  and  is  shed  from  the  tracheae  with  the  cuticle 
when  the  insect  moults.  There  is  a  peculiarity  in  the  structure  of  the 
chitinous  layer  of  the  wall  of  the  tracheae  that  has  attracted  much 
attention.  It  is  furnished  with  thickenings  which  extend  spirally. 

These  give  the  tracheae  their  characteristic 
transversely  striated  appearance.  If  a 
piece  of  one  of  the  larger  tracheae  be 
pulled  apart  the  intima  will  tear  between 
the  folds  of  the  spiral  thickenings,  and 
the  latter  will  uncoil  from  within  the  tra- 
chea like  a  thread.  In  some  insects  there 
are  several  parallel  thickenings  of  the  in- 
tima ;  so  that  when  an  attempt  is  made 
to  uncoil  the  thread  a  ribbon-like  band 
is  produced,  composed  of  several  parallel 
threads.  I  have  often  observed  this  in  the 
FIG.  54.  -section  of  trachea  and  larger  tracheae  of  the  larva  Q{'  Corydalus. 

'"TUp,     cniral      thr^aHc     arf*     wantincr      in     fVif> 
-1  ne     Spiral     UireaaS     are     Wanting      in     tne 

smaller  terminal  portions  of  the  tracheae. 

In  many  adult  insects,  especially  those  that  have  great  powers 
of  flight,  the  tracheae  are  enlarged  in  many  places  so  as  to  form 
air-sacs.  These  doubtless  tend  to  lessen  the  specific  gravity  of  the 
insect.  The  spiral  thickenings  are  not  developed  in  the  intima  of 
these  air-sacs. 

Although  insects  are,  strictly  speaking,  air-breathing  animals, 
many  of  them,  as  is  well  known,  live  in  the  water.  The  study  of 
the  ways  in  which  aquatic  insects  breathe  is  a  very  interesting  one  ; 
it  presents  to  us  many  wonderful  modifications  of  structure.  Some 
of  the  more  common  of  these  are  described  in  subsequent  pages  of 
this  book  ;  in  this  place  I  can  only  make  a  few  generalizations. 

The  various  modes  of  respiration  of  aquatic  insects  may  be  clas- 
sified under  two  heads  :  first,  those  in  which  the  insect  obtains  its 
air  from  above  the  surface  of  the  water  ;  second,  those  in  which  the 
insect  breathes  the  air  that  is  mechanically  mixed  with  the  water. 

With  many  aquatic  insects  the  spiracles  open  beneath  the  wings, 
which  are  folded  upon  the  abdomen.  The  insect  by  coming  to  the 
surface  of  the  water  and  lifting  the  tips  of  its  wings  forms  a  cavity 
beneath  them  into  which  the  air  rushes.  The  insect  can  then  swim 
through  the  water  carrying  this  air  with  it  in  a  position  where  it  can 
be  respired.  When  the  air  becomes  impure,  the  insect  rises  to  the 


THE  ANATOMY  OF  INSECTS.  41 

surface,  forces  out  the  air  from  beneath  its  wings  and  takes  in  a  new 
supply.  Water-beetles  and  aquatic  bugs  afford  familiar  examples  of 
this  mode  of  respiration. 

Some  insects  are  provided  with  long  tubes  connected  with  their 
spiracles  by  means  of  which  they  can  draw  their  supply  of  air  from 
above  the  surface  of  the  water  while  they  crawl  upon  the  bottom  of 
shallow  ponds.  Our  most  common  illustrations  of  this  are  bugs  of 
the  family  Nepidae ;  but  the  most  remarkable  development  of  this 
kind  is  exhibited  by  certain  Dipterous  larvae  of  the  family  Syrphidae, 
known  as  Rat-tailed  Maggots. 

Although  there  are  many  insects  that  live  in  the  water  and  draw 
their  supply  of  air  from  above  it,  the  greater  number  of  aquatic  in- 
sects breathe,  as  do  fishes,  the  air  that  is  mixed  with  the  water.  This 
is  accomplished  by  organs  known  as  tracheal  gills.  These  are  hair- 
like  or  more  or  less  plate-like  expansions  of  the  body-wall,  abun- 
dantly supplied  with  tracheae.  These  tracheae  divide  and  subdivide, 
and  their  terminations  or  fine  branches  are  separated  from  the 
water  that  bathes  the  organ  only  by  its  thin  walls.  In  this  way  the 
air  contained  in  the  tracheae  is  separated  from  the  air  in  the  water 
only  by  a  delicate  membrane  which  admits  of  the  transfer  of  gases 
between  them.  It  will  be  observed  that  the  difference  between  a 
tracheal  gill  and  a  true  gill  (as  of  fishes,  Crustacea,  etc.)  is  that  the 
true  gill  is  supplied  with  vessels  containing  blood,  which  is  purified 
by  being  brought  in  contact  with  the  air  in  the  water,  while  the 
tracheal  gill  is  supplied  with  tracheae  containing  air  to  be  purified. 

Tracheal  gills  are  usually  borne  by  the  abdomen, 
sometimes"  by  the  thorax,  and  in  case  of  one  genus  of 
Stone-flies  by  the  head.  They  pertain  almost  exclusively 
to  the  immature  stages  of  insects ;  but  Stone-flies  of  the 
genus  Pteronarcys  retain  them  throughout  their  existence. 

Tracheal  gills  vary  greatly  in  form  ;  in  Corydalus  they 
are  hair-like  and  occur  in  tufts  near  the  lateral  margins 
of  the  abdominal  segments ;  in  the  Caddice-worms  they 
are  thread-like,  more  or  less  branched,  and  irregularly  dis- 
tributed over  the  surface  of  the  abdomen  ;  and  in  certain     Fig.  55.— 
Dragon-flies  (Agrioninae)  they  are  in   the  form   of  large        gmheof 
plate-like  caudal  appendages,  Fig.  55. 

The  respiratory  movements  of 'insects  have  been  carefully  studied 
by  Plateau*  and  others.  These  movements  consist  in  general  of 

*  See  account  by  Plateau,  in  "  The  Cockroach,"  by  Miall  and  Denny,  p.  159. 


42  AN  INTRODUCTION   TO  ENTOMOLOGY. 

alternate  contraction  and  recovery  of  the  figure  of  the  abdomen  in 
two  dimensions,  viz.,  vertical  and  transverse.  , 

The  Reproductive  Organs. — In  insects  the  male  and  female  repro- 
ductive organs  are  placed  in  different  individuals.  In  many  insects 
there  are  marked  external  sexual  differences  of  size,  form,  coloring, 
or  character  of  appendages.  In  others  it  is  difficult  to  determine 
the  sex  without  dissection.  The  reproductive  organs  vary  greatly  in 
form,  but  agree  in  certain  general  characteristics.  They  are  con- 
tained in  the  abdomen,  are  paired,  and  usually  open  by  a  common 
duct  near  the  caudal  end  of  the  body.  (In  the  May-flies  and  Ear- 
wigs the  reproductive  organs  of  each  side  have  a  distinct  opening.) 

In  the  female  there  is  in  the  abdominal  cavity  on  each  side  an 
ovary.  This  is  a  compound  organ  consisting  of  a  series  of  parallel 
tubes  opening  into  a  common  oviduct.  Sometimes  these  tubes  are 
attached  to  each  other  so  as  to  form  a  compact  body ;  in  other  spe- 
cies each  tube  is  free  for  a  greater  or  less  part  of  its  length.  These 
tubes  are  tapering  in  outline,  the  larger  end  being  joined  to  the  ovi- 
duct. Within  these  tubes,  even  in  the  larval  state,  may  be  found 
the  developing  eggs,  each  tube  containing  a  single  row  of  them  grad- 
ually increasing  in  size  from  the  small  end  of  the  tube  towards  its 
opening  into  the  oviduct.  The  oviducts  of  the  two  sides  unite  a  short 
distance  from  the  external  opening  and  form  the  vagina.  There  are 
usually  accessory  glands  opening  into  the  vagina,  whose  secretions 
serve  to  surround  the  eggs  or  to  fasten  them  to  the  objects  upon 
which  they  are  laid.  Connected  also  with  the  vagina  are  one  or 
more  pouches,  the  receptdcula  seminis,  within  which  the  reproduc- 
tive fluid  of  the  male  is  received  and  stored.  This  fluid  retains  its 
fertilizing  properties  for  a  long  time.  Thus  the  queen-bee  or  ant 
pairs  but  once,  though  she  may  continue  to  lay  fertile  eggs  for  years. 
The  fertilization  of  the  eggs  of  insects  takes  place  at  the  time  they 
are  laid.  There  is  in  one  end  of  the  shell  of  the  egg  one  or  more 
pores  known  as  mlcropyles.  Through  these  the  spermatozoa  enter 
the  egg,  as  it  passes  the  opening  of  the  receptacula  seminis. 

In  some  cases,  at  least,  it  is  not  necessary  that  an  egg  should  be 
fertilized  in  order  that  the  embryo  should  develop.  This  has  been 
proven  with  the  Honey-bee.  But  so  far  as  is  known  the  unfertil- 
ized eggs  of  the  bet  produce  only  males. 

The  organs  of  the  male  consist  of  a  number  of  tubular  glands, 
often  coiled  together  so  as  to  form  an  apparently  compact  body, 
the  ttstes.  These  like  the  ovaries  are  paired  and  located  in  the 
abdominal  cavity.  The  efferent  ducts  of  these  glands,  the  vdsa  defe- 


THE  ANATOMY  OF  INSECTS.  43 

rentia,  like  the  oviducts  unite  and  form  an  unpaired  duct,  the  dfictus 
ejaculatorius.     Accessory  glands  open  into  this  duct. 

All  insects  are  developed  from  eggs.  But  there  are  some  ap- 
parent exceptions.  Thus  many  flies  retain  their  eggs  till  after  they 
are  hatched,  if  a  proper  place  for  laying  them  is  not  found  earlier ; 
and  in  some  flies  (the  Pupipara)  the  young  attajn  a  considerable 
development  before  they  are  born.  In  the  Plant-lice  (Aphididae) 
there  is  a  remarkable  alternation  of  reproduction  by  budding  with 
the  sexual  reproduction. 


CHAPTER  III. 
THE  ORDERS  OF  THE  HEXAPODA. 

IN  a  preceding  chapter  the  distinguishing  characters  of  insects 
have  been  discussed.  We  have  now  to  study  the  manner  in  which 
the  class  Hexapoda  is  divided  into  its  principal  divisions  or  orders. 
Regarding  this  subject,  there  is  at  the  present  time  much  difference 
of  opinion,  Naturalists  are  not  agreed  as  to  the  limits  of  the  differ- 
ent orders  of  insects.  The  number  recognized  in  standard  works 
varies  from  seven  to  more  than  twice  that  number. 

Although  the  question  is  an  exceedingly  difficult  one,  it  is  an 
easy  matter  to  state  where  the  differences  of  opinion  lie.  And  these 
differences  do  not  complicate  the  subject  greatly. 

More  than  a  century  ago  Linnaeus  recognized  seven  orders  of 
insects.  These  he  named  Coleoptera,  Hemiptera,  Lepidoptera, 
Neuroptera,  Hymenoptera,  Diptera,  and  Aptera.  Five  of  these 
orders  were  well  founded  ;  and  two  were  not.  The  Aptera  was  soon 
regarded  as  an  unnatural  group.  It  included  various  wingless  in- 
sects, which  later  entomologists  have  distributed  among  the  other 
orders.  The  Linnaean  order-  Hemiptera  included  all  four-winged  in- 
sects in  which  the  front  wings  are  half  horny  and  half  membranous. 
But  here  Linnaeus  by  confining  his  attention  to  the  wing  characters 
alone  fell  into  error.  The  order  Hemiptera  as  defined  by  him  in- 
cluded at  least  two  distinct  orders ;  and  those  members  of  it  with 
biting  mouth-parts  were  separated  a  little  later  by  Olivier  as  the 
order  Orthoptera.  Thus  by  the  suppression  of  the  Aptera,  and  the 
erection  of  the  Orthoptera,  the  number  of  orders  remained  the  same 
as  proposed  by  Linnaeus.  And  with  these  two  modifications  the 
Linnaean  classification  has  been  very  generally  accepted  to  this  day. 

The  modified  Linnaean  system  indicated  above  is  very  simple 
and  for  this  reason  many  entomologists  are  loath  to  propose  alter- 
ations in  it.  But  there  are  certain  places  in  which  this  classification 
brings  together  insects  which  differ  too  widely  to  be  classed  in  the 
same  order.  The  science  of  Entomology,  however,  is  not  yet  far 
enough  advanced  for  any  one  to  state  with  any  degree  of  certainty 
in  just  how  many  cases  this  is  true. 

One  of  the  principal  points  in  which   there  are  differences  of 


THE  ORDERS  OF  THE  HEXAPODA.  45 

opinion  is  in  regard  to  the  order  Neuroptera.  In  this  order  as  de- 
fined by  Linnaeus  there  are  included  insects  with  a  complete  meta- 
morphosis as  well  as  those  with  an  incomplete  one.  So  radical  a 
difference  as  this  can  hardly  be  expected  to  occur  within  the  limits 
of  the  same  order.*  For  this  reason  those  families  in  which  the 
transformation  is  an  incomplete  one  were  separated  by  Erichson  as 
the  order  Pseudoneuroptera ;  and  the  term  Neuroptera  restricted  to 
those  in  which  the  metamorphosis  is  complete.  This  adds  one  to 
the  list  of  orders.  In  the  following  pages  I  have  considered  the 
order  Pseudoneuroptera,  as  distinct  from  the  order  Neuroptera. 

Gerstaeker  and  some  others  of  the  German  entomologists  do  not 
stop  with  the  separation  of  the  Pseudoneuroptera  from  the  Neurop- 
tera. They  hold  that  there  is  no  important  character  separating  the 
former  order  from  the  Orthoptera ;  and  they  therefore  include  in  the 
order  Orthoptera  not  only  the  insects  commonly  placed  there  by  the 
English  and  American  entomologists,  but  also  those  of  the  Linnaean 
order  Neuroptera  in  which  the  metamorphosis  is  an  incomplete  one. 

We  have,  therefore,  three  slightly  differing  systems,  which  agree 
as  to  the  orders  Hemiptera,  Lepidoptera,  Diptera,  Coleoptera,  and 
Hymenoptera,  but  differ  as  to  the  other  orders.  These  differences 
are  represented  in  the  following  table.  It  will  be  noted  that  al- 
though the  classification  of  Olivier  and  that  of  Gerstaeker  present 
the  same  names,  these  are  used  with  widely  different  signification. 
The  Orthoptera  of  Gerstaeker  includes  much  more,  and  the  Neurop- 
tera much  less  than  in  the  classification  of  Olivier. 

OLIVIER.  ERICHSON.  GERSTAEKER. 

Orthoptera.  Orthoptera.  } 

Orthoptera. 

C  Pseudoneuroptera.  } 
Neuroptera. 

( Neuroptera.  Neuroptera. 

Although  the  Linnaean  system  slightly  -modified  in  one  or  another 
of  the  three  ways  just  indicated  is  still  very  generally  accepted, 
there  are  many  entomologists  who  hold  that  further  modifications 
should  be  made.  There  are  certain  families,  as  the  Earwigs,  Fleas, 
Thrips,  and  others,  each  of  which  differs  greatly  from  the  typical 
representatives  of  the  order  in  which  it  was  at  first  placed.  Each 
of  these  families  have  in  turn  been  raised  to  the  rank  of  an  order. 
But  there  is  as  yet  little  agreement  among  systematists  as  to  how 

*  The  males  of  the  Coccids  are  the  only  insects  which  present  an  exception  in  this 
respect. 
4 


46 


AN  INTRODUCTION   TO  ENTOMOLOGY. 


many  of  them  are  entitled  to  this  rank.  In  the  following  pages 
most  of  these  families  are  discussed  under  the  head  of  the  orders  in 
which  they  have  been  most  commonly  placed  ;  in  each  case,  how- 
ever, the  possible  rank  of  the  group  as  a  distinct  order  is  indicated. 

There  is  one  more  proposed  modification  of  the  Linnaean  system 
which  should  be  noticed  in  this  place.  Nearly  all  of  the  families  in 
the  orders  Pseudoneuroptera  and  Neuroptera  are  remarkably  dis- 
tinct. Each  family  differs  from  the  other  families  in  the  same  order 
in  much  more  important  characters  than  usually  distinguish  families 
in  the  other  orders.  At  the  same  time  the  characters  which  distin- 
guish either  of  these  orders  are  not  well  marked.  For  these  reasons 
Professor  Brauer  holds  that  the  Pseudoneuroptera  and  the  Neurop- 
tera are  not  natural  orders,  but  that  the  former  group  includes  four 
and  the  latter  three  distinct  orders. 

Although  in  some  respects  (as,  for  example,  in  the  classing  to- 
gether of  the  Termitidae,  Psocidae,  and  Mallophaga  as  an  order,  the 
Corrodentia)  I  cannot  follow  Professor  Brauer,  I  am  inclined  to  think 
that  in  the  main  the  school  of  entomologists  which  he  represents  is  in 
the  right  as  regards  the  number  and  characters  of  the  orders  of  the 
Hexapoda.  And  I  frankly  confess  that  in  adhering  so  closely  to 
the  old  classification  I  have  been  greatly  influenced  by  a  desire  to 
make  my  presentation  of  the  subject  as  simple  as  possible,  and  by 
the  belief  that  an  elementary  text-book  should  follow  rather  than 
lead  in  matters  of  this  kind.  I  have,  however,  endeavored  to  pre- 
sent the  facts  in  such  a  manner  as  to  clearly  indicate  the  ideas  of 
the  different  schools. 

On  the  following  page  two  lists  of  orders  are  given.  In  the  first 
column  are  indicated  the  orders  recognized  in  this  work  ;  in  the  sec- 
ond column  are  indicated  the  various  other  orders  that  have  been 
proposed.  The  reasons  in  each  case  for  considering  these  smaller 
groups  orders  is  given  later,  under  the  special  discussion  of  the 
group. 

LISTS   OF   ORDERS   OF   HEXAPODA. 
I.  II. 


I.  THYSANURA. 


II.  PSEUDONEUROPTERA. 


THYSANURA. 

PLECTOPTERA.     (Ephemertda^ 
ODONATA. 
PLECOPTERA. 
CORRODENTIA.     (Mallophaga,    Psoctda,   Ter- 
mitidce^) 


THE  ORDERS  OF  THE  HEX  A  POD  A.  47 

I.  II. 

III.  ORTHOPTERA.  \  DERMAPTERA.    (Forficulida) 

(  ORTHOPTERA.  f 

IV.  PHYSOPODA.  PHYSOPODA. 

V.  HEMIPTERA.  \  HOMOPTERA. 

f  HETEROPTERA. 

f  NEUROPTERA.     (Sialidce,  Hemerobtdce.) 
VI.  NEUROPTERA.  4  MECAPTERA.    (Panorpidte.) 

ITRICHOPTERA.     (Phryganeidcs^ 
VII.  LEPIDOPTERA.  LEPIDOPTERA. 

VIII.    DIPTERA.  \  CETERA. 

\  SlPHONAPTERA.      (PultCldcB^ 

(  STREPSIPTERA.    (Stylopida'.) 
IX.  COLEOPTERA.  4  ACHREIOPTERA.     (Platypsyllidtz.) 

ICOLEOPTERA. 

X.  HYMENOPTERA.     \y          HYMENOPTERA. 

It  is  not  my  purpose  in  this  place  to  discuss  the  distinguishing 
features  of  the  orders  of  insects.  But  it  seems  worth  while  to 
present  here  a  brief  tabular  statement  of  the  more  important  ordinal 
characters.  This  table  will  aid  the  student  in  formulating  his  ideas 
as  to  the  characters  of  the  orders  and  as  to  the  relations  of  the 
orders  to  each  other.  It  should  be  borne  in  mind,  however,  that  a 
linear  arrangement  is  not  a  natural  one ;  it  is  simply  a  necessity  of 
book-making.  The  arrangement  adopted  here  is  the  one  that  I  be- 
lieve best  indicates  the  relative  rank  of  the  various  orders  taken  as 
a  whole. 

There  is  no  doubt  that  the  Thysanura  is  the  lowest  of  the  orders.  But  the 
position  assigned  to  any  one  of  the  other  orders  is  open  to  dispute.  Thus  we 
find  in  the  Orthoptera  certain  forms  (the  earwigs)  which  show  as  strong  affini- 
ties to  the  Thysanura  as  do  any  of  the  Pseudoneuroptera.  And  some  entomol- 
ogists hold  that  the  Physopoda  is  the  lowest  of  the  orders  of  winged  insects. 

.To  enter  into  a  detailed  discussion  of  the  reasons  which  have  led  me  to 
adopt  the  sequence  of  the  orders  given  in  the  following  pages  would  be  beyond 
the  scope  of  this  work  ;  but  the  following  generalizations  will  indicate  the 
more  important  ones. 

That  series  of  orders  in  which  the  insects  undergo  an  incomplete  metamor- 
phosis (the  Ametabold)  is  undoubtedly  lower  than  that  (\\-\zMetabold)  in  which 
the  transformation  is  a  complete  one.  The  chief  objection  to  placing  the  latter 
series  as  a  whole  above  the  former  is  the  wide  separation  thus  brought  about 
between  the  Neuroptera  and  Pseudoneuroptera.  I  have  felt,  however,  that 
this  was  the  least  of  two  evils,  Within  the  lower  series  the  two  orders  in 
which  the  mouth-parts  are  formed  for  biting  are  placed  lower  on  this  account 
than  the  two  orders  in  which  the  mouth  is  more  highly  modified.  Of  these 


48  AN  INTRODUCTION   TO  ENTOMOLOGY. 

two  orders  of  biting  insects  there  can  be  but  little  doubt  that  certain  members 
of  the  Orthoptera  (the  crickets  and  katydids)  reach  a  higher  specialization  in 
structure  than  do  any  of  the  Pseudoneuroptera.  The  Physopoda  are  undoubt- 
edly lower  in  structure  than  the  Hemiptera;  but  they  resemble  that  order 
more  closely  than  any  other  in  the  structure  of  the  mouth-parts.  The  deter- 
mination of  the  proper  sequence  of  the  orders  of  the  Metabola  is  a  much  more 
difficult  question  than  that  of  the  Ametabola.  Of  the  five  orders  which  con- 
stitute the  higher  series,  entomologists  are  agreed  that  the  Neuroptera  are  the 
lowest  in  structure.  The  Hymenoptera  are  placed  highest  with  almost  equal 
unanimity ;  not  only  do  these  insects  exhibit  a  very  high  degree  of  organiza- 
tion, but  the  development  of  the  instinctive  powers  reached  by  bees,  wasps, 
and  ants  is  greater  than  that  attained  by  any  other  insects.  The  Lepidoptera 
are  placed  next  to  the  Neuroptera  on  account  of  the  affinities  between  the  cad- 
dice-flies  and  moths.  On  the  other  hand,  the  higher  Lepidoptera  and  the  Dip- 
tera  resemble  each  other  in  the  structure  of  the  thorax.  And  the  pupae  of 
certain  Diptera  (Cecidomyidae  and  Tipulidae)  resemble  more  or  less  the  pupae 
of  Lepidoptera.  The  Coleoptera  are  assigned  to  the  next  highest  place,  with  the 
belief  that  their  complexity  of  structure  entitles  them  to  this  rank  ;  but  with 
no  intention  of  suggesting  affinities  with  the  Hymenoptera  on  the  one  hand 
or  the  Diptera  on  the  other. 

Following  the  tabular  statement  of  the  more  important  charac- 
ters of  the  orders  of  insects,  there  is  given  a  table  to  aid  the  student 
in  classifying  specimens.  This  table  is  purely  artificial  and  includes 
only  adult  insects.  I  have  endeavored,  however,  to  include  in  it  all 
of  the  aberrant  forms,  those  which  the  young  student  would  find 
difficult  to  classify. 


TABULAR   STATEMENT   OF   THE   MORE   IMPORTANT    CHARAC- 
TERS  OF   THE   ORDERS   OF   HEXAPODA. 

A.  Wingless  insects  which  show  no  evidences  of  having  descended  from 
winged  ancestors  {i.e.,  in  which  the  thorax  is  simple  in  structure),  and  which 
undergo  no  metamorphosis.  (Synaptera.*)  I.  THYSANURA. 

AA.  Winged  insects;  or  wingless  insects  in  which  this  condition  is  the  result 
of  a  retrograde  development,  indicated  by  the  complicated  structure  of  the 
thorax,  or  by  the  presence  of  wings  in  closely  allied  forms.     (Pterygogenea^) 
B.  Insects  with  an  incomplete  metamorphosis.     (Ametabola^) 
C.  Mouth-parts  formed  for  biting  ;  i.e.,  with  the  mandibles  and  maxillae  in 
the  form  of  jaws. 
D.  The  two  pairs  of  wings  similar  in  structure,  membranous. 

II.  PSEUDONEUROPTERA. 

DD.  The  first  pair  of  wings  parchment-like;    the  second  pair  membra- 
nous, and  folded  in  plaits  longitudinally.  III.  ORTHOPTERA. 
CC.  Mouth-parts  intermediate  in  structure  between  those  of  the  biting 
insects  and  those  of  the  sucking  insects  •  viz.,  with  bristle-like  mandibles* 
and  with  flat,  triangular  maxillae.  IV.  PHYSOPODA. 


THE  ORDERS  OF  THE  HEXAPODA.  49 

CCC.  Mouth-parts  formed  for  sucking;  viz.,  with  the  mandibles  and  max- 
illae bristle-like.  V.  HEMIPTERA. 
BB.  Insects  with  a  complete  metamorphosis.     (Metabola.) 
C.   Mouth-parts  formed  for  biting;  viz.,  both  mandibles  and  maxillae  in  the 
form  of  jaws. 

D.  The  two  pairs  of  wings  similar  in  structure,  membranous,  with  many 
veins  and  cells.  '^  VI.  NEUROPTERA. 

DD.  The  first  pair  of  wings  much  thickened  (horny)  throughout  their 
entire  length,  and  meeting  in  a  straight  line  down  the  back ;  the  sec- 
ond pair  membranous.  IX.  COLEOPTERA. 
CC.  Mouth-parts  formed  for  both  biting  and  sucking ;  viz.,  with  the  man- 
dibles in  the  form  of  jaws  ;  and  with  the  maxillae  and  labium  fitted  for 
taking  liquid  food.     Both  pairs  of  wings  membranous,  with  few  veins 
and  cells.                                                                        X.  HYMENOPTERA. 
CCC.  Mouth-parts  formed  for  sucking. 

D.  With  four  wings  clothed  with  minute  imbricated  scales ;  mandibles 
rudimentary;  maxillae  developed  into  a  sucking  tube. 

VII.  LEPIDOPTERA. 

DD.  With  only  two  wings ;  the   hind  wings  represented  by  a  pair  of 
knobbed,  thread-like  organs  ;  mandibles  and  maxillae  bristle-like. 

VIII.   DlPTERA. 

r 

TABLE   FOR  DETERMINING  THE  ORDERS  OF   HEXAPODA. 

(This  table  includes  only  adult  insects.) 

A.  Wingless  or  with  rudimentary  wings. 

B.  Mandibles  and  maxillae  retracted  within  the  cavity  of  the  head  so  that 
only  their  apices  are  visible.  I.  THYSANURA. 

BB.  Mandibles  and  maxillae  more  or  less  prominent  and  fitted  for  biting. 
C.  Head  with  long,  trunk-like  beak.     (Boreus.)  VI.  NEUROPTERA. 

CC.  Head  not  prolonged  into  a  trunk. 

D.  Louse-like  insects  of  small  size;  body  less  than  one-sixth  inch  in 
length.     (Book-lice  and  Bird-lice.)  II.  PSEUDONEUROPTERA. 

DD.  Insects  of  various  forms,  but  not  louse-like,  and,  except  in  the  case 
of  some  ants5,  with  the  body  more  than  one-sixth  inch  in  length. 
E.  Abdomen  with   short,  conical,  compressed,  many-jointed  caudal 
appendages.     (Cockroaches.)  III.  ORTHOPTERA. 

EE.  Abdomen  without  jointed  caudal  appendages. 

F.   Legs,  fitted  for  jumping.     (Wingless  Locusts,  Grasshoppers,  and 
Crickets.)  III.  ORTHOPTERA. 

FF.  Legs  fitted  for  running. 

G.  Abdomen  broadly  joined  to  thorax. 

H.  Body  linear.     (Walking-sticks.)  III.  ORTHOPTERA. 

HH.  Body  white  and  somewhat  ant-like  in  form.     (Termes.) 

II.  PSEUDONEUROPTERA. 

HHH.  Body  neither  linear  nor  ant-like  in   form%   (Wingless 
Fire-fly  et  al.)  IX.  COLEOPTERA. 


5<D  AN  INTRODUCTION   TO  ENTOMOLOGY. 

GG.  Base  of  abdomen  strongly  constricted.     (Ants  et  a/.J 

X.  HYMENOPTERA. 

BBB.  Mouth-parts  formed  for  sucking. 

C.  Small  abnormal  insects  in  which  the  body  is  either  scale-like  or  gall- 
like  in  form,  or  grub-like,  and  clothed  with  wax.  The  waxy  covering 
may  be  in  the  form  of  powder,  of  large  tufts  or  plates,  of  a  continuous 
layer,  or  of  a  thin  scale,  beneath  which  the  insect  lives.  (CoccidcE.} 

VI.  HEMIPTERA. 

CC.  Body  more  or  less  covered  with  minute  scales,  or  with  thick  long 

hairs.     Prothorax   not  free  (i.e.,  closely  united  with  the  mesothorax). 

Mouth-parts  usually  consisting  of  a  long  "  tongue"  rolled  beneath  the 

head.  VII.  LEPIDOPTERA. 

CCC.  Body  naked,  or  with  isolated  or  bristle-like  hairs. 

D.  Prothorax  not  well  developed,  inconspicuous  or  invisible  from  above. 
Tarsi  five-jointed.  Mouth-parts  developed  into  an  unjointed  trunk  ; 
palpi  present.  VIII.  DIPTERA. 

DD.  Prothorax  well  developed. 

E.  Body  strongly  compressed  ;  tarsi  five-jointed.     (Fleas?) 

VIII.  DIPTERA. 

EE.  Body  not  compressed  ;  tarsi  one-,  two-,  or  three-jointed. 
F.  Last  joint  of  tarsi  bladder-like  or  hoof-like  in  form  and  without 
claws;  mouth-parts  forming  a  triangular,  unjointed  beak;  palpi 
present.  IV.  PHYSOPODA. 

FF.  Last  joint  of  tarsi  not  bladder-like,  and  furnished  with  one  or 
two  claws  ;  mouth-parts  forming  a  slender,  usually  jointed  beak  ; 
palpi  wanting.  V.  HEMIPTERA. 

AA.  Winged. 

B.  With  two  wings. 
C.  First  pair  of  wings  transformed  into  club-shaped  appendages.     (Stylo- 

pldj>?)  IX.   COLEOPTERA. 

CC.  Second  pair  of  wings  rudimentary  or  wanting. 
D.  Wings  horny,  leathery,  or  parchment-like. 

E.  Mouth-parts  formed  for  sucking.     Wings  leathery,  shortened,  or 
membranous  at  the  tip.  V.  HEMIPTERA. 

EE.  Mouth-parts  formed  for  biting.     Jaws  distinct. 

F.  Wings  horny,  without  veins.     Hind  legs  not  fitted  for  jumping. 

IX.  COLEOPTERA. 

FF.  Wings  parchment-like,  with  a  network  of  veins.  Hind  legs 
fitted  for  jumping.  III.  ORTHOPTERA. 

DD.  Wings  membranous. 

E.  Abdomen  with  caudal  filaments.     Mouth-parts  rudimentary. 
F.  Halteres  wanting.     (Cloeon  and  C<znis,  in  Ephemeridcz?) 

IV.    PSEUDONEUROPTERA. 

FF.  Halteres  present  (males  of  Coccidse).  V.   HEMIPTERA. 

EE.  Abdomen  without  caudal  filaments.     Halteres  in  place  of  second 

wings.     Mouth-parts  formed  for  sucking.  VIII.  DIPTERA. 

BB.  Witr^four  wings. 

C,  The  two  pairs  of  wings  unlike  in  structure.     Prothorax  freely  movable. 


THE  ORDERS  OF  THE  HEXAPODA.  51 

D.  Front  wings  leathery  at  base,  and   membranous  at  tip,  often  over- 
lapping.    Mouth-parts  formed  for  sucking.  V.  HEMIPTERA. 
DD.   Front  wings  of  same  texture  throughout. 

E.   Front   wings   horny   or  leathery,    forming  veinless   wing-covers. 
(Elytra?) 

F.  Abdomen  with  caudal  appendages  in  the  form  of  movable  for- 
ceps.    (Earwigs'.}  III.  ORTHOPTERA. 
FF.  Abdomen  without  forcep-like  appendages.      IX.  COLEOPTERA. 
EE.  Front  wings  leathery  or  parchment-like,  with  a  network  of  veins. 
F.  Under  wings  not  folded.     Mouth-parts  formed  for  sucking. 

V.  HEMIPTERA. 

FF.  Under  wings  folded  lengthwise.    Mouth-parts  formed  for  biting. 

III.  ORTHOPTERA. 
CC.  The  two  pairs  of  wings  similar,  membranous. 

D.  Last  joint  of  tarsi  bladder-like  or  hoof-like  in  form  and  without  claws. 

IV.  PHYSOPODA. 
DD.  Last  joint  of  tarsi  not  bladder-like. 

E.  Wings  entirely  or  for  the  greater  part  clothed  with  scales.    Mouth- 
parts  formed  for  sucking.  VII.  LEPIDOPTERA. 
EE.  Wings  naked,  transparent,  or  thinly  clothed  with  hairs. 

F.  Mouth-parts  arising  from  the  hinder  part  of  the  lower  surface  of 
the  head,  and  consisting  of  bristle-like  organs  enclosed  in  a  jointed 
sheath.  (Homoptera.}  V.  HEMIPTERA. 

FF.  Mouth-parts  in  normal  position.     Mandibles  not  bristle-like. 
G.  Wings  net-veined,  with  many  veins  and  cross-veins. 
H.  Tarsi  consisting  of  less  than  five  segments. 

II.   PSEUDONEUROPTERA. 

HH.  Tarsi  consisting  of  five  segments. 

I.  Abdomen    with    setiform,    many-jointed    anal    filaments. 
(Certain  May-flies?)  II.  PSEUDONEUROPTERA. 

II.  Abdomen  without  many-jointed  anal  filaments. 

VI.  NEUROPTERA. 

GG.  Wings  with   branching  veins  and   comparatively  few  cross- 
veins,  or  veinless. 
H.  Tarsi  two-  or  three-jointed. 

I.  Posterior  wings  smaller  than  the  anterior.     (Psocida.) 

II.  PSEUDONEUROPTERA. 

II.  Posterior  wings  as  large  or  larger  than  the  anterior  ones. 
(Certain  Stone-flies?)  II.  PSEUDONEUROPTERA. 

HH.  Tarsi  four-  or  five-jointed. 

I.  Abdomen    with    setiform,    many-jointed    anal   filaments. 
(Certain  May- flies?)  II.  PSEUDONEUROPTERA. 

II.  Abdomen  without  many-jointed  anal  filaments. 

J.  Prothorax  horny.  First  wings  larger  than  the  second, 
naked  or  imperceptibly  hairy.  Second  wings  without  or 
with  few,  usually  simple,  veins.  Jaws  (mandibles)  well  de- 
veloped. Palpi  small.  X.  HYMENOPTERA. 


52  AN  INTRODUCTION   TO  ENTOMOLOGY. 

JJ.  Prothorax  membranous  or,  at  the  most,  parchment-like. 
Second  wings  as  large  as  or  larger  than  the  first,  folded 
lengthwise,  with  many  branching  veins.  First  wings 
naked  or  thinly  clothed  with  hair.  Jaws  (mandibles)  in- 
conspicuous. Palpi  long,  Moth  like  insects.  (Phryga- 
neida.}  VI.  NEUROPTERA. 


CHAPTER  IV. 


Order  I.— THYSANURA.* 
(Bristle-tails,  Spring-tails,  Fish-moths,  et  al.) 

The  members  of  this  order  are  wingless  insects  which  undergo  no 
metamorphosis,  the  larval  form  being  retained  by  the  adult.  The 
mandibles  and  maxillce  are  retracted  within  the  cavity  of  the  head, 
so  that  only  their  apices  are  visible;  they  have,  however,  some  freedom 
of  motion,  and  can  be  used  for  biting  and  chewing  soft  substances. 
True  compound  eyes  are  rarely  present ;  but  in  some  genera  there  is  a 
group  of  agglomerated  simple  eyes  on  each  side  of  the  head.  The 
abdomen  is  sometimes  furnished  with  rudimentary  legs  ;  and  in  one 
genus  there  are  well-developed  abdominal  legs. 

This  order  comprises  chiefly  minute  insects,  which  live  on  decay- 
ing vegetable  matter,  and  can  be  found 
abundantly  in  damp  situations ;  some 
species,  however,  live  in  warm  and  dry 
places,  and  feed  upon  starched  clothing, 
the  binding  of  books,  and  other  dry 
substances.  In  the  more  common  spe- 
cies, the  body  is  either  elongated,  and 
furnished  with  six  well-developed  legs, 
and  two  or  more  long,  many-jointed, 
caudal  appendages  (Fig.  56)  ;  or  short, 


FIG.  56. — Ltpisma  saccharina, 
(After  Lubbock.) 


FIG.  ST.—Pafirius/uscus.     (After 
Lubbock.) 


thick,  and  with    a    forked    springing    apparatus,    bent   under    the 
abdomen,  instead  of  the  thread-like  caudal  appendages  (Fig.  57). 

*  Thysantlra:  thysanos  (SvcraroS),  a  tassel;  oura  (ovpd),  the  tail. 


54 


AN  INTRODUCTION   TO  ENTOMOLOGY. 


Owing  to  the  small  size  of  these  insects,  the  majority  of  them 
escape  the  attention  of  all  except  the  more  careful  students  of 
nature.  The  order  is,  however,  of  great  interest  to  entomologists ; 
for  it  includes  the  lowest  or  simplest  of  the  true  insects ;  and  in  it 
are  found  forms  which  show  close  affinities  to  the  next  lower  class, 
the  Myriapoda.  It  is  thus  one  of  the  connecting  links  of  which  we 
hear  so  much  in  these  days;  and  in  it  are,  doubtless,  forms  which 
more  closely  resemble  than  any  other  living  species  those  which  in 
ancient  geological  times  were  the  first  Hexapoda  to  appear  on  the 
earth. 

The  low  rank,  of  these  insects  is  indicated  in  many  ways.  The 
mouth-parts  are  of  a  primitive  form  ;  wings  are  never  developed  ; 
and  the  insects  undergo  no  metamorphosis,  the  larval  form  being 
retained  by  the  adult. 

The  absence  of  wings  in  this  order  is  believed  to  represent  the  primitive  con- 
dition of  these  insects.  None  of  the  species  show  any  indication  of  the  devel- 
opment of  these  organs.  And  the  thorax  does  not  present  that  complication 
of  structure  which  is  the  result  of  the  development  of  wing-muscles.  In  each 
of  the  higher  orders  we  find  wingless  species;  but  in  these  cases  there  is  good 
reason  for  believing  that  the  wingless  condition  is  the  result  of  a  retrograde 
development.  In  some  cases  this  degradation  is  the  result  of  parasitic  habits, 
as  with  lice,  fleas, and  mady  other  parasites;  in  other  instances  it  is  the  result 
of  the  separation  of  the  species  into  several  castes,  of  which  some  do  not  re- 
quire wings,  as  the  workers  and  soldiers  among  Termes,  and  the  sedentary 
generations  of  the  Aphides. 

Upon  the  distinction  given  above  Professor  Brauer  separates  the  insects  into 
two  classes.  The  first  includes  only  the  Thysanura  ;  this  he  calls  the  Aptery- 

gogenea,  or  "  originally  wingless  insects  ;" 
it  coincides  with  the  super-order  Syndp- 
tera  of  Packard.  The  second  class  Brauer 
terms  the  Pterygogenea,  or  "  originally 
winged  insects." 

The  form  of  the  mouth-parts  of 
the  Thysanura  is  very  different  from 
that  seen  elsewhere  in  the  class 
Hexapoda.  Here  the  mandibles 
and  maxillae,  although  fitted  for  bit- 
ing, are  retracted  within  the  head, 
instead  of  being  attached  externally 
as  is  the  case  with  the  higher  in- 
bial  palpus-  sects  whose  mouth-parts  are  formed 

for  biting.     Fig.  58,  I,  shows  the  relation  of  the  jaws  to  the  wall  of 
the  head  in  a  common  spring-tail,  one  of  the  Entomobryidce.     In  this 


FIG.  58.— Mouth-parts  of  a  Spriner-tail,  Ento- 
(Drawn   by  J.  M.  Stedman,  un- 


THYSANURA.  55 

figure  the  mandibles  are  represented  by  a  continuous  line,  and  the 
maxillae  by  a  dotted  one.  It  will  be  observed  that  only  the  tips  of 
these  organs  project  from  the  cavity  of  the  head. 

There  are,  as  pointed  out  by  Meinert  and  by  Lubbock,  among  the  Hexapods 
three  principal  forms  of  mouth  : 

"  First,  the  mandibulate,  in  which  the  mandibles  and  maxillae  are  attached 
externally,  and  are  more  or  less  powerful  and  adapted  for  biting  and  chewing. 

"  Second,  the  suctorial,  in  which  the  mandibles  and  maxillae  are  attached 
internally,  and  are  not  opposite,  but  parallel,  and  intended  for  pricking. 

"Third,  the  type  presented  by  the  Thysanura,  in  which  the  mandibles  and 
maxillae  are  attached  internally,  and  are  far  from  strong,  but  still  have  some 
freedom  of  motion,  and  can  be  used  for  biting  and  chewing  soft  substances. 

The  Thysanura  includes  three  sub-orders  ;  these  can  be  separated 
by  the  following  table : 

A.  With   well-developed   abdominal   legs,  insect   resembling  a   Myriapod  in 
form.  I.  SYMPHYLA. 

AA.  With  only  six  well-developed  legs, 

B.  Without  ventral   abdominal  sucker.     Caudal  appendages  bristle-like  and 
many-jointed,  or  in  the  form  of  a  pair  of  forceps.  II.  CINURA. 

BB.  With  a  bifurcated  sucker  or  tubercle  on  the  ventral  aspect  of  the  first 
abdominal  segment.  Abdomen  with  a  springing  apparatus,  or  without  ap- 
pendages. HI.  COLLEMBOLA. 

Sub-Order  I.— SYMPHYLA.* 

This  sub-order  has  been  erected  for  the  reception  of  a  single 
genus,  Scolopendrella.  This  genus  includes  certain  minute  insects 
the  zoological  position  of  which  is  in  doubt.  All  of  the  known  species 
are  less  than  7  mm.  (.28  in.)  in  length.  The  general  form  of  the 
body  resembles  that  of  a  Centipede ;  and  as  with  the  centipedes, 
each  abdominal  segment  bears  a  pair  of  legs.  But  except  in  the 
presence  of  these  abdominal  legs  the  structure  of  the  body  is  more 
like  that  of  the  Cinura  than  that  of  the  Myriapods.  And  the  legs 
are  five-jointed  and  end  in  two  claws  as  in  the  Cinura ;  while  in  the 
Myriapoda  there  are  six  joints,  and  always  a  single  large  claw. 

Sub-Order  II.— ClNURA.f 
(Bristle-tails  and  Fish-moths^) 

Among  the  pests  that  annoy  the  housekeeper  there  is  one  which 
is  wingless,  but  can  run  rapidly,  and  which  has  long  thread-like  ap- 

*  Symphyla:  syn  (<rvv),  together;  phyla   (<f>vkrf),  tribe, 
f  Cindra:  cineo  (^iveao),  to  move;  oura  (ovpd),  a  tail. 


AN  INTRODUCTION   TO   ENTOMOLOGY. 


pendages  at  the  caudal  end  of  its  body.  This  insect,  on  account  of 
the  minute,  shining  scales  with  which  its  body  is  clothed,  is  known 
as  the  fish-moth.  And  it  is  the  most  familiar  representative  of  the 
sub-order  Cinura.  Other  species  occur  beneath  the  bark  of  decay- 
ing trees  and  in  similar  situations.  The  caudal  end  of  the  abdomen 
is  usually  furnished  with  slender  bristle-like  appendages.  These 
suggest  the  popular  name  Bristle-tails  applied  to  the  sub-order  as  a 
whole. 

The  body  consists  of  the  head,  three  thoracic  and  ten  well-marked 
abdominal  segments.     The  antennae  are  large,  many-jointed,  some- 
times longer  than  the  body,  and  generally  tapering  towards  the  end. 
The  most  remarkable  character  presented  by  this 
order  is  a  series  of  sub-abdominal  appendages.     These 
are  well  shown  in  Machilis  (see  Fig.  59).     Similar  ap- 
pendages are  attached  to  the  coxae  of  the  second  and 
third  pairs  of  thoracic  legs.     These  abdominal  appen- 
dages  are    regarded    as   rudimentary   legs.     We   have 
here,  therefore,  a  condition  approaching  that  exhibited 
by  Scolopendrella. 

The  Cinura  (Thysanura  of  Lubbock)  is  divided  into 
three  families.     These  can  be  distinguished  as  follows: 

A.     Body  not  clothed  with  scales. 

B.     Caudal     appendages    unsegmented, 
horny  and  pincer-like. 

I.  JAPYGID^E. 

BB.    Caudal    appendages    many-jointed 
and  thread-like. 

II.  CAMPODEID^E. 
A  A.  Body  clothed  with  scales. 

III.  LEPISMID.E. 

Family  I.  JAPYGID^E. — The  most  obvious  char- 
acter  of   this  family  is    presented    by  the  caudal 
appendages.     These   resemble   those    of    earwigs, 
being  in  the  form  of  horny  forceps.     The  body  is 
not  clothed  with  scales;    eyes  are  wanting.     The  FlG  ( 
palpi   are   short;    and    the   segments   of   the   ab- 
domen are  of  nearly  equal  width.     The  sub-abdominal  appendages 
are  represented  by  groups  of  hairs. 

Only  a  single  genus,  Jdpyx,  has  been  described.  Jdpyx  subterrd- 
neus  "  is  found  under  stones  at  the  mouth  of  a  small  grotto  near  the 
Mammoth  Cave." 

Family  II.     CAMPODEID^:. — This  family  resembles  the  preced- 


FIG.  59.— Ventral 
aspect  of  Ma- 
chilis,  showing 
appendages. 


THYSANURA. 


57 


FIG.  61.  —  Camfodea 
staphylinus.  (After 
Lubbock.) 


ing  in  that  the  body  is  not  clothed  with  scales,  the  eyes  are  wanting, 

and  the  segments  of   the  abdomen  are  of  nearly 

equal   width.      But    the    caudal    appendages   are 

long,  thread-like,  and  many-jointed.     To  each  of 

the  first  seven  abdominal  segments  there  is  at- 
tached a  pair  of  ventral  appendages,  the  rudi- 
mentary legs  already  mentioned. 

Two  genera  have  been  described.     Campodea 

has   two    caudal   appendages,    and   the   palpi  are 

minute.      In    Nicoletlna    there   are   three   caudal 

appendages,  and  the  palpi  are  long. 

Family  III.  LEPISMID/E. — In  this   family  the 

body  is  clothed  with  scales ;  the  palpi  are  short ; 

and  the  abdomen  tapers  towards  the  caudal  end. 

The  eyes  are  large,  compound,  and  contiguous  in 

Mdchilis ;  and    small  and   far   apart    in   Lepisma. 

The  sub-abdominal  appendages    are    well   devel- 
oped  in   Machilis ;    in    Le- 
pisma they  are  confined  to 
two  of  the  posterior  segments,  and  represented 
by  groups  of  stiff  hairs  on  the  anterior  ones. 
The  three  described  genera  are  distinguished 
as  follows : 

A.  Prothorax  much  enlarged,  and  the  abdomen  ta- 
pering rapidly,  so  that  the* body  is  almost  heart- 
shaped  ;  caudal  appendages  short.  LEPISMINA. 

A  A.  Body  more  elongated  ;  caudal  appendages  long. 
B.  Eyes  large  and  contiguous.  MACHILIS. 

BB.  Eyes  small  and  far  apart.  LEPISMA. 

The  Fish-moth,  Lepisma  saccharina  (Fig. 
62),  is  a  well-known  pest  in  some  parts  of  the 
country.  It  is  silvery  white  with  a  yellowish 
tinge  about  the  antennae  and  legs ;  it  measures 
8  mm.  (.31  in.)  in  length.  It  injures  clothing, 
especially  starched  clothes ;  and  the  bindings 
of  books.  An  instance  was  reported  to  me  where  they  caused 
the  paper  to  cleave  from  the  walls  of  a  house  by  feeding  upon 
the  starch  with  which  it  was  fastened  in  place. 


FIG.    62.  —  Lepisma    saccha" 
rina.    (After  Lubbock.) 


58  AN  INTRODUCTION    TO  ENTOMOLOGY, 

Sub-Order  I.  —  COLLEMBOLA.* 
(Spring-tails^) 

To  this  sub-order  belong  certain  minute  insects  which  have  re- 
ceived the  common  name  Spring-tails.  They  are  often  of  micro- 
scopic size.  The  majority  live  on  decaying  matter  ;  and  are  very 
common  under  stones  and  decayed  leaves  and  wood,  in  the  chinks 
and  crevices  of  bark,  among  moss,  and  on  herbage  in  damp  places. 
Sometimes  they  occur  abundantly  in  winter  on  the  surface  of  snow  ; 
where  they  appear  as  minute  black  specks,  which  spring  away  on 
either  side  from  our  feet  as  we  walk.  And  some  species  collect  in 
great  numbers  on  the  surface  of  standing  water. 

The  body  consists  of  the  head,  three  thoracic  and  six  abdominal 
segments.  The  abdominal  segments  are  not  well  marked  in  some 
forms.  No  compound  eyes  exist  in  this  sub-order.  There  is,  how- 
ever, usually  a  group  of  simple  eyes  on  each  side  of  the  head.  The 
antennae  consist  of  but  few,  four  to  eight,  segments.  The  mouth- 
parts  are  formed  for  biting,  except  in  Anoura,  where  the  mandibles 
and  maxillae  are  wanting. 

The  name  Collembola  refers  to  a  curious  organ  situated  on  the 

.&*->$.  ventral  aspect  of  the  first  abdominal  seg- 

'*^*,  jr  ,,,.._  merit,  the  ventral  tube  or  sucker.      "  In 

"ffl^V^UB      fiftk        Podura,  Lipura,  and  the  allied  genera,  this 

JjP  K       organ  is  a  simple  tubercle  ;   divided  into 

B^      two    halves   by   a   central   slit  ;    in   other 

y^^^^^^^^BW^     genera,  as,  for  instance,  in  Orchesella  and 

TomoceruS)  the  tubercle  is  enlarged,  and 


FIG.  63.-/«^.   (After     becomes  a  tube  divided  at  the  free  end 


into  two  lobes.     In  the  Smynthuridae  and 

Papiriidae  the  organ  receives  a  still  further  and  remarkable  devel- 
opment ;  from  the  end  of  the  tube  the  animal  can  project  two 
long,  delicate  tubes  provided  at  their  extremity  with  two  glands." 
(Lubbock.)  By  means  of  this  sucker  and  the  fluid  excreted  by  its 
glands  these  insects  are  enabled  to  cling  to  the  lower  surface  of 
smooth  objects. 

The  popular  name  Spring-tails  was  suggested  for  these  insects 
by  a  peculiar  leaping  apparatus  which  most  of  them  possess.  It 
consists  of  a  long  appendage  of  either  the  fourth  or  fifth  abdominal 
segment,  which  extends  under  the  abdomen  towards  the  head. 

*  CollSmbola;  colon  (K&Xov),  a  limb;  embole  (e^/SoA??),  a  throwing. 


THYSANURA. 


59 


This  appendage  consists  of  a  basal  segment  and  two  appendages ; 
which  are  sometimes  two-jointed,  and  sometimes  consist  of  a  single 
piece  each.  This  appendage  constitutes  the  spring.  On  the  ven- 
tral side  of  the  third  abdominal  segment  in  certain  genera  is  also  an 
appendage,  which  is  termed  the  catch.  This  catch  passes  between 
the  branches  of  the  spring  and  holds  it  in  place.  By  relieving  the 
spring  and  extending  it  suddenly  the  insect  is  able  to  throw  itself  to 
a  considerable  distance. 

Some  of  the  Collembola  are  clothed  with  scales,  resembling  in 
this  respect  butterflies  and  moths.  These  scales  are  very  minute, 
and  wonderfully  sculptured.  The  markings  on  them  are  so  minute 
that  it  requires  a  very  good  microscope  to  resolve  them.  On  this 
account  they  have  been  much  used  as  test  objects  for  microscopes 
under  the  name  of  "  Podura  scales." 

The  most  remarkable  feature  in  the  structure  of  the  Collembola 
is  that  in  nearly  the  entire  sub-order  tracheae  are  wanting ;  while  in 
certain  members,  Smynthnis,  there  is  a  well-developed  respiratory 
system.  The  difference  is  a  great  one  to  exist  between  genera  other- 
wise so  closely  allied. 

In  certain  respects  the  Collembola  is  the  lowest  of  the  three  sub-orders  of 
the  Thysanura  ;  and  it  is  so  placed  in  some  of  the  standard  works  on  entomol- 
ogy. The  mouth-parts  are  very  rudimentary  in  this  sub-order;  and  the  tra- 
cheae are  rarely  developed.  But  it  has  seemed  more  natural  to  me  to  follow 
the  Myriapoda  by  Scolopendrilla ;  and  to  place  next  the  sub-order  Cinura, 
containing,  as  it  does,  forms  with  rudimentary  abdominal  legs.  We  have  thus 
an  unbroken  series  from  the  Myriapodous  to  the  Hexapodous  condition.  In 
the  Collembola  we  have  insects  which,  while  retaining  a  very  primitive  form 
of  the  mouth-parts  and  of  the  respiratory  system  (the  result  of  their  con- 
tinuing to  feed  on  soft  substances,  and  to  live  in  damp  situations),  present  a 
much  modified  form  of  the  body,  and  the  development  of  peculiar  special  or- 
gans, the  spring  and  the  ventral  tube  or  sucker.  We  thus  see  well  illustrated 
the  difficulties,  referred  to  elsewhere,  of  any  attempt  to  arrange  animals  in  a 
linear  series. 

The  Collembola  is  divided  by  Lubbock  into  six  families.  These 
can  be  separated  by  the  following  table : 

A.  Saltatorial. 
B.  Body  globular. 
C.  Terminal  segment  of  abdomen  short,  with  whorls  of  hair. 

i.  PAPIRIID^:. 

CC.  Terminal  segment  long,  ringed.  2.  SMYNTHURID.E. 

BB.   Body  cylindrical. 


do  AN  INTRODUCTION   TO  ENTOMOLOGY. 

C.  The  spring  an  appendage  of  the  penultimate  (fifth)  abdominal  segment. 

3.  ENTOMOBRYID/E.* 

CC.  The  spring  an  appendage  of  the  antipenultimate  (fourth)  abdominal 
segment.  4.  PODURID/E. 

AA.  Non-saltatorial. 

B.  Mouth  mandibulate.  5.  LIPURID^E. 

BB.  Mouth  suctorial.  6.  ANOURIDTE. 

Family  I.  PAPIRIID^E. — Two  genera  of  this  family  have  been 
established.  Papirius  is  characterized  by  four-jointed  antennae  ;  and 
Dicyrtoma  by  having  the  antennae  eight-jointed.  A  large  species 
from  Maine  and  Massachusetts,  measuring  2^  mm.  (o.i  in.)  in  length, 
is  described  by  Packard  under  the  name  Papirius  marmordtus.  It  is 
marbled  with  deep  dull  lilac  and  pearl-colored  lines  and  spots. 

Family  II.  SMYNTHURID.E. — Only  a  single  genus  of  this  family, 
Smynthurus,  has  been  described.  In  this  genus  the  antennae  are 
four-jointed,  and  the  respiratory  system  is  well  developed.  The 
presence  of  tracheae  enable  these  insects  to  live  in  drier  situations 
than  can  other  members  of  the  sub-order.  The  Garden  Flea,  Smyn- 
thurus hortensis,  is  described  by  Fitch  as  occurring  abundantly  in 
May  and  June,  upon  the  leaves  of  young  cabbage,  turnip,  cucumber, 
and  various  other  plants,  and  also  on  the  ground.  It  is  dull  black, 
with  the  head,  legs,  and  bases  of  the  antennae  rust-color.  Several 
other  species  of  this  genus  have  been  described  by  Fitch  and 
Packard. 

Family  III.  ENTOMOBRYID^E. — This  is  by  far  the  largest  family 
in  this  order ;  nine  genera  having  been  described.  These  can  be 
separated  by  the  following  table,  which  is  from  one  given  by  Lub- 
bock: 

A.  Antennae  six-jointed.  ORCHESELLA. 

AA.  Antennae  four-  or  five-jointed. 
B.  With  scales. 

C.  Terminal  segments  of  antennae  ringed. 
D.  Two  terminal  segments  ringed. 

E.  Eyes  seven  in  each  group.  TOMOCERUS. 

E.  Eyes  absent.  TRITOMURUS. 

D.  Third  segment  simple.  TEMPLETONIA. 

CC.  Terminal  segment  of  antennae  simple. 

D.  No  eyes.  BECKIA. 

DD.  With  eyes. 
E.  Head  exposed.  SEI'RA. 

*  The  Degeeriadae  of  Lubbock.     The  generic  name  Degeeria  falls  owing  to  its  hav- 
ing been  previously  used  in  the  Diptera. 


THYSANURA.  6l 

EE.  Head  more  or  less  concealed  under  the  thorax.  LEPIDOCYRTUS. 
BB.  Without  scales. 

C.  Abdominal  segments  unequal.  ENTOMftBRYA. 

CC.  Abdominal  segments  subequal.  ISOTOMA. 

Family  IV.  PODURID^E. — The  Poduridcz  comprises  two  genera, 
Achorutes,  in  which  the  tarsi  have  two  claws,  and  Podura,  in  which 
there  is  but  a  single  claw  on  each  tarsus.  Certain  species  of  each 
genus  are  found  on  the  surface  of  standing  water.  Our  common 
"  Snow-flea"  is  Achorutes  nivicola.  This  is  sometimes  a  pest  where 
maple-sugar  is  made ;  the  insects  collecting  in  large  quantities  in 
the  sap. 

Family  V.  LlPURID^E. — The  body  is  cylindrical  in  form ;  there 
is  no  saltatorial  appendage  ;  and  the  mouth-parts  are  formed  for 
biting.  Only  a  single  genus,  Lipura,  has  been  described. 

Family  VI.  ANOURID^E. — This  family  resembles  the  preceding 
in  the  cylindrical  form  of  the  body,  and  in  the  absence  of  a  saltato- 
rial appendage ;  but  it  differs  from  all  other  members  of  the  Thysa- 
nura,  in  having  the  mouth-parts  formed  for  sucking.  The  mouth- 
parts  are  exceedingly  rudimentary;  there  being  neither  mandibles  nor 
maxillae.  There  is  but  a  single  genus,  Anoura,  known.  The  name 
of  this  genus  will  doubtless  be  changed,  as  it  is  preoccupied  by  a 
genus  of  bats. 


CHAPTER  V. 
Order  VI.— PSEUDONEUROPTERA.* 

(Dragon-flies,  May-flies,  Stone-flies,  et  al.) 

The  members  of  this  order  have  four  wings;  these  are  membran- 
ous, and  usually  furnished  with  numerous  veins.  The  mouth-parts 
are  formed  for  biting  except  in  one  family  (Ephemeridce],  where  they 
are  rudimentary.  The  metamorphosis  is  incomplete. 

The  insects  which  are  here  classed  as  the  order  Pseudoneuroptera, 
and  those  which  in  a  later  part  of  the  book  are  termed  Neuroptera 
were  formerly  united  in  a  single  order,  under  the  name  Neuroptera. 
This  union  was  based  upon  the  similarity  of  the  characters  presented 
by  the  mouth-parts  and  the  wings  in  the  two  groups.  But  there  is 
a  radical  difference  in  the  nature  of  the  transformations.  In  one 
the  metamorphosis  is  incomplete ;  in  the  other  it  is  complete. 
Although  it  is  difficult  to  find  characters  presented  by  the  adult 
insects  which  will  separate  these  two  groups,  this  difference  in  the 
transformations  indicates  that  they  are  not  closely  enough  related 
to  be  placed  in  the  same  order.  The  term  Neuroptera  has,  there- 
fore, been  restricted  to  those  with  a  complete  metamorphosis ;  and 
the  name  Pseudoneuroptera,  i.e.,  false  Neuroptera,  applied  to  those 
with  an  incomplete  metamorphosis. 

The  beginning  student,  in  the  classification  of  his  specimens,  will 
find  some  difficulty  in  separating  these  two  orders.  But  this  can  be 
done  by  means  of  the  table  on  pages  49  to  52.  And  as  soon  as  one 
becomes  familiar  with  the  families  included  in  these  orders  there 
will  be  no  necessity  for  the  use  of  the  table. 

In  the  linear  arrangement  I  have  adopted,  these  two  closely- 
allied  orders  become  widely  separated ;  this  results  from  the  separa- 
tion of  the  orders  into  two  series,  in  one  of  which  the  metamorpho- 
sis is  incomplete,  in  the  other  complete. 

The  Pseudoneuroptera  is  not  a  well-marked  order.  Not  only  is 
it  difficult  to  distinguish  it  from  the  Neuroptera,  but  it  includes 
families  which  differ  greatly  from  each  other.  The  differences  be- 


*  PseudoneurSptera:  pseudes  (^et>5^5),  false;  Neuroptera. 


PSE  UDONE  UROP  TERA  .  63 

tween  the  families  are  much  greater  than  is  usual  between  the  families 
of  the  same  order.  On  this  account  it  is  proposed  by  Professor 
Brauer  to  break  the  Pseudoneuroptera  up  into  at  least  four  orders, 
one  for  each  of  the  first  three  families,  and  one  for  the  last  three. 
It  remains  to  be  seen  whether  this  multiplication  of  the  orders  will 
be  accepted  by  entomologists  generally. 

Owing  to  the  great  differences  which  exist  between  the  families 
of  the  Pseudoneuroptera,  I  will  not  attempt  to  make  further  gener- 
alizations respecting  the  group  in  this  place. 

The  Pseudoneuroptera  is  represented  in  this  country  by  six 
families,  These  can  be  separated  by  the  following  table  : 

TABLE   OF   FAMILIES   OF   PSEUDONEUROPTERA.* 

A.  With  four  or  two  welt-developed  wings. 

B.   Antennae  inconspicuous,  awl-shaped,  short  and  slender. 
C.   First  and  second  pair  of  wings  nearly  of  the  same  length  ;  tarsi  three- 
jointed.  2.  LIBELLULID.E. 

CC.  Second  pair  of  wings  either  smaller  or  wanting  ;  tarsi  four-  or  five- 
jointed.  i.  EPHEMERID^E. 

BB.  Antennae   usually  conspicuous,  setiform,  filiform,  clavate,  capitate,  or 
pectinate. 
C.  Tarsi  two-  or  three-jointed. 

D.  Second  pair  of  wings  the  smaller.  5.  PSOCIDJE. 

DD.  Second  pair  of  wings  broader,  or  at  least  of  the  same  size  as  the 

first  pair.  3.  PERLID^E. 

CC.  Tarsi  four-jointed  ;  wings  equal.  6.  TERMITID^E. 

AA.  Wingless,  or  with  rudimentary  wings. 

B.  Tarsi  four-jointed.  6.  TERMITID^:. 

BB.  Tarsi  three-jointed. 
C.  Wingless,  or  with  two  rudimentary  wings  of  a  leathery  substance. 

5.  PSOCID^E. 

CC.  Four  rudimentary  wings,  still  with  distinct  venation.        3.  PERLID^:. 
BBB.  Tarsi  two-  or  one-jointed.  4.  MALLOPHAGID^E. 


Family  I.  — 
Order  PLECTOPTERA  of  some  authors.:): 

(May-flies.) 

The  May-flies  or  Ephemerids  are  often  very  common  insects  in  the 
vicinity  of  streams,  ponds,  and  lakes  ;  frequently  the  surface  of  such 
bodies  of  water  is  thickly  strewn  with  them.  They  are  attracted  by 

*  After  Baron  Osten  Sacken,  in  Hagen's  Synopsis. 

f  Ephemgridae,  Ephgmera  :  ephemeron  (efifaepov),  a  may-fly. 

£  Plectoptera  ;  plectos  (TrAeKToS),  plaited  ;  pteron  (Ttrepoy),  a  wing. 


AN  INTRODUCTION   TO  ENTOMOLOGY. 


lights;  and  it  is  not  an  uncommon  occurrence  in  summer-time  to  see 
hundreds  of  them  flying  about  a  single  street-lamp. 

They  are  very  fragile  insects, 
with  large  delicate  fore  wings, 
with  the  hind  wings  much  smaller 
or  wanting,  and  with  the  abdo- 
men furnished  at  its  caudal  end 
with  either  two  or  three  many- 
jointed,  thread-like  appendages 
(Figs.  64  and  640). 

The     body     is     smooth,     not 


FIG.  64.— May-fly. 


FIG.  640.— Canis. 


clothed  with  scales  or  hairs.  The  head  is  free,  with  atrophied 
mouth-parts,  and  inconspicuous  antennae.  These  are  composed 
of  two  short  stout  segments  succeeded  by  a  slender  many-jointed 
bristle.  The  thorax  is  robust,  with  the  mesothorax  predomi- 
nant. The  great  development  of  this  segment  is  correlated 
with  the  large  size  of  the  fore  wings.  The  abdomen  is  long, 
soft,  and  composed  of  ten  segments.  In  the  male  there  is  a  pair 
of  clasping  organs  placed  ventrally  at  the  extremity  of  the  ninth  seg- 
ment ;  these  are  usually  two-,  three-,  or  four-jointed,  and  are  termed 
the  forceps-limbs.  Just  behind  the  forceps-limbs  are  the  paired  ex- 
ternal sexual  organs.  The  form  of  the  external  parts  of  the  repro- 
ductive organs  is  remarkable ;  each  vas  deferens  and  each  oviduct 
has  a  separate  opening.  In  the  male  these  openings  are  between  the 
ninth  and  tenth  abdominal  segments,  as  indicated  above  ;  in  the  fe- 
male, between  the  seventh  and  eighth. 

The  May-flies  have  received  considerable  attention  in  popular 
writings  on  account  of  their  ephemeral  existence  in  the  adult  state. 
All  have  read  of  the  insects  that  live  but  a  day.  Reference  is  made 
in  these  accounts  to  members  of  this  family ;  and  although  the  popu- 
lar idea  is  fallacious,  it  has  some  foundation  in  fact.  Strictly  speak- 
ing, the  May-flies  are  long-lived  insects ;  some  species  appear  twice 
annually,  once  in  the  spring,  and  again  in  the  autumn  ;  but  as  a  rule 
one,  two,  or  even  three  years  are  required  for  the  development  of  a 


PSE  UDONE  UROP  TERA.  65 

generation.  The  greater  part  of  this  time  is  passed,  however,  beneath 
the  surface  of  water ;  and  after  the  insect  emerges  into  the  air  and 
assumes  the  adult  form  its  existence  is  very  brief.  With  many 
species  the  individuals  leave  the  water,  undergo  two  transformations, 
mate,  lay  their  eggs,  and  die  in  the  course  of  an  evening  or  early 
morning.  And  although  the  adults  of  many  genera  live  several  days, 
the  existence  of  these  insects  is  very  short  compared  with  members 
of  other  families. 

The  females  lay  their  eggs  in  water.  Some  short-lived  species  dis- 
charge the  contents  of  each  ovary  in  a  mass.  Specimens  are  often 
found  in  which  there  project  from  the  caudal  end  of  the  body  two 
parallel  subcylindrical  masses  of  eggs,  one  protruding  from  each  of 
the  openings  of  the  oviducts.  Egg-clusters  of  this  kind  "laid  upon 
the  water  rapidly  disintergrate,  so  as  to  let  the  eggs  sink  broad-cast 
upon  the  river-bed.  The  les's  perishable  species  extrude  their  eggs 
gradually,  part  at  a  time,  and  deposit  them  in  one  or  the  other  of 
the  following  manners  :  either  the  mother  alights  upon  the  water  at 
intervals  to  wash  off  the  eggs  that  have  issued  from  the  mouths  of 
the  oviducts  during  her  flight;  or  else  she  creeps  down  into  the 
water — enclosed  within  a  film  of  air,  with  her  wings  collapsed  so  as  to 
overlie  the  abdomen  in  the  form  of  an  acute  narrowly  linear  bundle, 
and  with  her  setae  closed  together — to  lay  her  eggs  upon  the  under 
side  of  stones,  disposing  them  in  rounded  patches,  in  a  single  layer 
evenly  spread,  and  in  mutual  contiguity."  (EATON.) 

With  most  May-flies  the  general  form  of  the  body  in  the  immature 
stages  resembles  somewhat  that  of  the  adult.  The  newly-hatched 
nymphs  respire  through  the  integument  at  large.  During  the  first 
few  days  after  their  birth  the  young  cast  their  skin  several  times, 
the  intervals  between  the  moultings  lengthening  by  degrees.  Rudi- 
ments of  tracheal  gills  begin  to  appear  when  the  insect 
is  eight  or  ten  days  old  ;  they  bud  forth  from  the  hinder 
lateral  angles  of  some  or  all  of  the  first  seven  abdominal 
segments ;  and,  like  the  parts  of  the  mouth,  are  modi- 
fied considerably  in  detail  before  they  acquire  their 
ultimate  shapes.  They  may  be  either  thread-like, 
tufted,  or  plate-like  in  form.  In  Oligoneura  and  folia 
there  is  a  pair  of  tracheal  gills  attached  to  the  base  of 
the  maxillae.  This  is  a  striking  exception  to  the  general 
rule  that  external  organs  of  respiration  do  not  appear 
on  the  head  of  insects.  Fig.  65  represents  a  nymph  of  a  May- 


66  AN  INTRODUCTION   TO  ENTOMOLOGY. 

fly,  a  common  representative  of  this  family  found  under  stones  in 
the  beds  of  streams  at  Ithaca. 

"  May-fly  nymphs  mostly  feed  upon  either  mud  or  minute  aquatic 
vegetation,  such  as  covered  stones  and  the  larger  plants  ;  but  (judg- 
ing by  their  mandibles  and  maxillae)  some  must  be  predaceous. 
Many  of  them  live  in  concealment  in  the  banks  or  under  stones  in 
the  bed  of  streams,  rivers,  and  lakes ;  others  ramble  openly  amongst 
water-weeds  and  swim  with  celerity."  (EATON.)  The  nymphs  of 
May-flies  undergo  many  moults  ;  Cloeon,  according  to  the  observations 
of  Lubbock,  sheds  its  skin  twenty-one  times.  In  this  insects  there 
are  no  traces  of  wings  until  the  ninth  state  ;  then  the  hinder  lateral 
angles  of  dorsal  aspect  of  the  meso-  and  metathorax  become  slightly 
produced.  With  each  successive  moult  these  prolongations  become 
more  marked,  until  in  the  twentieth  state,  the  last  passed  under 
water,  the  rudimentary  wings  cover  half  or  the  whole  of  the  third 
abdominal  segment.  The  wing-cases  are  not  inverted  (see  page  6). 

Most  members  of  this  family  exhibit  a  remarkable  peculiarity  in 
their  development.  After  the  insect  leaves  the  water  and  has  ap- 
parently assumed  the  adult  form,  that  is,  after  direct  respiration 
through  the  spiracles  has  been  established,  and  the  wings  have  be- 
come fully  expanded,  it  moults  again.  This  is  the  only  instance  in 
which  insects  with  fully  developed  wings  cast  their  skin.  The  term 
subimago  is  applied  to  this  stage  between  the  nymph  and  the  final 
form  of  the  insect.  With  some  species  the  duration  of  the  sub- 
imago  stage  is  only  a  few  minutes  ;  the  insect  moults  on  leaving  the 
water  ;  flies  a  short  distance;  and  moults  again.  In  others  this  stage 
lasts  twenty-four  hours  or  more. 

The  adults  of  the  Ephemeridae  eat  nothing.  Not  only  is  the 
period  of  existence  in  this  state  so  brief  that  food  in  addition  to 
that  taken  in  the  nymph  state  is  unnecessary,  but  the  imperfect  con- 
dition of  the  mouth  precludes  the  taking  of  nourishment.  With 
many  species  of  May-flies  there  is  great  uniformity  in  the  date  of 
maturing  of  the  individuals.  Thus  immense  swarms  of  them  will 
leave  the  water  at  about  the  same  time,  and  in  the  course  of  a  few 
days  pass  away ;  this  being  the  only  appearance  of  the  species  until 
another  generation  has  been  developed.  The  great  swarms  of 
"  Lake-flies  "  (Ephemera  simulans],  which  appear  along  our  northern 
lakes  about  the  third  week  in  July,  afford  good  illustrations  of  this 
peculiarity.  And  an  instance  is  on  record  where  May-flies  thronged 
to  the  gas-burners  in  a  store  and  actually  quenched  the  flames. 

The  Ephemeridae  are  regarded  as  the  lowest  living  representatives 


PSE  UDONE  UROP  TERA .  fy 

of  one  of  the  lines  of  development  of  winged  insects.  This  posi- 
tion is  indicated  by  fan-like  form  of  the  wings,  which  is  characteristic 
of  the  primordial  insects,  and  by  the  paired  openings  of  the  repro- 
ductive organs,  a  feature  not  found  in  highly  developed  animals. 

Our  representatives  of  this  family  have  not  been  thoroughly 
studied.  Eaton  in  his  monograph*  enumerates  less  than  one  hun- 
dred species  from  the  whole  of  North  America.  But  these  he  dis- 
tributes among  more  than  twenty  genera.  The  following  key  is 
based  on  the  characters  given  for  the  genera  and  groups  of  genera 
by  this  author.  It  will  aid  the  student  in  classifying  his  specimens ; 
but  it  should  be  regarded  as  merely  provisional. 

In  distinguishing  subordinate  groups  in  the  Ephemeridae  much  use  is  made 
of  the  venation  of  the  wings.  It  is  necessary  here  to  describe  only  that  of  the 
fore  wings.  The  system  adopted  is  that  of  Eaton. 

The  principal  nerves  of  the  fore  wing  show  a  tendency  to  be  segregated  into 
three  groups,  as  follows :  (Fig.  66.) 

C44..S. 


FIG.  66. — Fore  wing  of  May-fly. 

Group  I. — This  group  consists  of  three  veins,  which  communicate  directly 
with  the  thorax.  These  are  named  the  costa  (c),  subcosta  (sc},  and  radius  (r). 
The  costa  is  coincident  with  the  anterior  margin  of  the  wing;  and  the  sub- 
costa and  radius  are  nearly  parallel  with  it ;  the  three  veins  are  united  near  the 
base  of  the  wing  by  the  great  cross  vein. 

Group  II. — This  group  also  consists  of  three  principal  veins ;  but  the  first  of 
these  gives  off  a  prominent  branch  before  the  middle  of  the  -wing,  which  is 
termed  thes/cfor  (s).  The  sector  is  a  branch  of  the  cubitus  (cu)  ;  just  behind 
the  cubitus  is  the  prcebrdchial  (pr),  and  behind  that  the  postbrdchial  (60). 
This  group  of  veins  is  annexed  to  the  first  group,  or  terminates  in  the  wing 
membrane  adjacent  to  it,  close  to  the  base  of  the  wing. 

Group  III. — The  remaining  veins  constitute  the  third  group.  This  is  asso- 
ciated with  the  prominent  curved  or  angulated  crease  in  the  membrane  of  the 
wing,  which  forms  the  boundary  of  a  depression  near  the  base  of  the  wing. 
The  first  vein  of  this  group  is  the  anal  (a} ;  the  remaining  ones  are  termed  the 
axillary  veins  (ax1,  ax^^  ax*,  etc).  The  anal  vein  as  a  rule  subtends  directly  the 
anal  angle  of  the  wing;  in  one  group  of  genera  it  is  joined  at  its  base  to  the 
postbrachial  vein. 

*  A  Revisional  Monograph  of  Recent  Ephemeridae  or  May-flies,  by  the  Rev.  A.  E. 
Eaton.  This  work  is  to  form  Volume  III.  of  the  Trans,  of  the  Linn.  Soc.  of  London 
Only  four  parts  have  appeared  at  the  present  writing. 


68  AN  INTRODUCTION    TO  ENTOMOLOGY. 

TABLE   OF   GENERA   OF   THE   EPHEMERID^   OF   THE 
UNITED   STATES. 

'A.  At  the  base  of  the  fore  wing  the  anal  vein  (a]  meets  the  postbrachial  (po}\ 
hind  tarsi,  when  not  atrophied,  have  four  distinct  joints. 
B.  Female  with  the  hind  legs  longer  than  the  other  pairs ;  male  with  the 
forceps-limbs  sessile  upon  the  border  of  the  segment. 
C.  Includes  males  only.     Two  caudal  setae  in  both  genera. 

D.  Hinder  lateral  angles  of  the  9th  abdominal  segment  produced  into  a 
short,  tooth-like  spine.  JOLIA. 

DD.  Hinder  lateral  angles  of  the  abdominal  segments  subrectangular. 

POLYMITARCYS. 

CC.  Includes  females  only. 

D.  Two  caudal  setae.  JOLIA. 

DD.  Three  caudal  setae.  POLYMITARCYS. 

BB.  Fore  legs  of  females  at  least  as  long  as  hind  legs  ;  male  with  the  forceps- 
limbs  inserted  at  the  sides  of  the  terminal  border  of  a  short  transverse 
laminar  lobe  prolonged  from  the  segment. 
C.  Includes  males  only. 

D.  Median  seta  extremely  rudimentary. 

E.  Fore  leg  nearly  as  long  as  body;   the  tibia  about   ii  as   long  as 

femur.      Segments  of  caudal  setae  well  marked.      External  sexual 

organs  strongly  hooked.  HEXAGENIA. 

EE.   Fore  leg  about  half  as  long  as  body;   tibia  about  if  as  long  as 

femur.      Segments  of  caudal  setae  inconspicuous.      External  sexual 

organs  nearly  straight.  PENTAGENIA. 

DD.  Median  seta  about  as  long  as  the  others.  EPHEMERA. 

CC.  Includes  females  only. 

D.  Median  seta  extremely  rudimentary.  HEXAGENIA. 

DD.  Median  seta  about  as  long  as  the  others. 

E.  Abdominal  segments  6-10  together  constituting  about  fof  the  ab- 
domen ;  segments  of  the  caudal  setae  well  marked.  EPHEMERA. 
EE.  Abdominal  segments  6-10  together   constituting  \  of  the  ab- 
domen ;  segments  of  the  caudal  setae  inconspicuous. 

PENTAGENIA. 

AA.  Anal  vein  (a)  of  fore  wing  does  not  directly  meet  the  postbrachial  vein 
(po),  but  is  connected  with  it  by  a  more  or  less  distinct  channel  of  circula- 
tion in  the  membrane. 

B.  The  channel  of  circulation  connecting  postbrachial  and  anal  veins  ob- 
solete (except  in  Ccznis,  a  two  winged  genus).  Hind  tarsi  with  tour 
distinct  joints. 

C.  Hind  wings  well  developed ;  with  a  sharply  denned,  almost  right-an- 
gled projection  situated  at  about  the  first  i  of  the  costal  margin. 

POTAMANTHUS. 

CC.  Hind  wings  of  small  or  moderate  proportions. 

D.  Hind  wings  either  gently  and  on  the  whole  continuously  curved  in 
front,  or  else  suddenly  retracted  in  the  middle  of  the  fore  margin. 
E.  Hind  tibia  usually  longer  than  the  femur,  rarely  subequal  to  it. 


PSE  UDONE  UROP  TERA .  69 

F.   Hind  wings  in  front  somewhat  depressed  in  the  middle. 
G.   Median  caudal  seta  subequal  to  the  others.       LEPTOPHLEBIA. 
GG.  Median  caudal  seta  far  shorter  than  the  others.  BLASTURUS. 
FF.   Hind  wing  strongly  angulated  in  front. 

G.  Basal  joint  of  forceps-limb  about  as  long  as  the  remainder ; 
female  with  ventral  lobe  of  segment  9  bifid  and  excised. 

HABROPHLEBIA. 

GG.   Basal  joint  of  foreceps-limb  very  short ;  joint  2  longer  than 
the  remainder;  female  with  ventral  lobe  of  segment  9  obtuse. 

CHOROTERPES. 

E.  Hind  tibia  rather  shorter  than  the  femur.  EPHEMERELLA. 

DD.  Costal  border  of  hind  wings  spurred  or  protuberant  at  about  the 
first  \  of  the  wing's  length. 

E.   Hind  wings  small,  and  extremely  narrow  ;  costal  projection  usually 
very  slender.  CENTROPTILUM. 

EE.  Hind  wings  broad,  oblong,  and  obtuse. 

F.  Hind  wings  with  numerous  cross-veins;  costal  projection  large 

and  rounded.  CALLIB/ETIS. 

FF.  Hind-wings  with  but  few  or  no  cross-veins;    costal  projection 

small  and  acute  or  wanting.  B^ETIS. 

CCC.  Hind  wings  wanting. 

D.  With  two  caudal  setae.  CLCEON. 

DD.  With  three  caudal  setae,    {fig.  640.)  OENIS. 

BB.  Channel  of  circulation  connecting  nerves  8  and  7  well  defined  ;   hind 
tarsi  with  five  distinct  joints. 

C.  Space  between  anal  (a)  and  first  axillary  (ax1)  veins  subtended  by  the 
outer  half  of  the  inner  margin  of  the  wing  and  the  anal  angle. 
D.  Tibise  of  the  hind  legs  longer  than,  or  at  least  subequal  in  length  to, 
the  tarsi. 

E.   Proximal  joint  of  the  hind  tarsus  shorter  than  the  second  joint. 
F.  Tarsal  claws  dissimilar  ;  costal  dilatation  of  the  hind  wing  acute. 

COLOBURUS. 

FF.  Tarsal  claws  alike,  narrow  and  hooked  ;  costal  dilatation  of  the 

hind  wing  obtuse.  CHIROTONETES. 

E.  Proximal  joint  of  the  hind  tarsus  subequal  to  the  second  joint; 

tarsal  claws  dissimilar;   costal  dilatation  of  the  hind  wing  almost 

right-angled,  AMELETUS 

DD.  Tibise  of  the  hind  legs  shorter  than  the  tarsi ;   proximal  joint 

the  hind  tarsus  longer  than  the  second  joint. 
CC.  Space  between  anal  (a)  and  first  axillary  (a*1)  veins  subtended  en- 

•     '  '  B^ETISCA. 


tirely  by  a  part  of  the  terminal  margin  of  the  wing. 
CC.  Space  between  anal  and  first  axiliar 
angle  and  a  part  of  the  terminal  margin. 


i,ii\^iy     uy     w.    £*«*•.*  »»  G>  . 

CCC    Space  between  anal  and  first  axillary  veins  subtended  by  the  anal 

•     '  HEPTAGENIA.* 


*  The  American  representatives  of  this  genus  have  been  distributed  by  Eaton 
among  five  genera,  which  are  distinguished  by  such  slight  and  inconstant  variations 
in  structure  that  I  have  been  unable  to  express  them  in  a  tabular  form. 


70  AN  INTRODUCTION   TO  ENTOMOLOGY. 

Family  II. — LIBELLULIDAE.* 
Order  ODOXATA  f  of  some  authors. 

(Dragon-flies^) 

The  Dragon-flies  are  very  common  insects  in  the  vicinity  of 
streams,  ponds,  and  lakes.  Many  of  them  are  of  large  size ;  and,  as 
they  fly  vigorously  during  the  day-time,  they  are  well  known.  They 
have  consequently  received  a  number  of  popular  names.  The  most 
common  of  these  used  in  this  country  are  Dragon-flies,  Darning- 
needles,  Spindles,  and  Snake-doctors. 

The  form  of  members  of  the  Libellulidae  is  very  characteristic 
(Fig.  67).  The  most  striking  features  are  the  long,  spindle-shaped 

body,  and  the  long,  nar- 
row, powerful  wings ;  of 
which  the  second  pair 
are  as  large  as  or  larger 
than  the  first  pair. 

The  head  of  a  dragon- 
fly is  large,  broad,  often 
semi-globose,  and  con- 
cave behind.  A  con- 
siderable part  of  its  sur- 
face is  occupied  by  the 
enormously  developed 

^.^-Plathentistrimaculata.    (From  Sanborn.)  Compound     eyes.       The 

antennae     are      short  ; 

they  consist  of  from  five  to  eight  segments ;  of  these  the  two  basal 
ones  are  thick,  the  others  form  a  bristle-like  organ.  The  mouth- 
parts  are  well  developed.  The  labrum  is  prominent ;  the  mandibles 
and  maxillae  are  both  strongly  toothed  ;  and  the  labium  consists  of 
three  large  lobes,  which  with  the  labrum  nearly  enclose  the  jaws 
when  at  rest.  The  thorax  is  large.  The  wings  are,  as  a  rule,  of 
nearly  similar  size  and  structure;  they  are  richly  netted  with  veins; 
and  the  front  border  of  each  is  divided  into  basal  and  apical  parts 
by  what  is  termed  the  nodus  (n,  Fig.  71).  The  veins  and  cells  are 
much  used  in  classification ;  the  terms  applied  to  them  are  given  in 
the  explanation  of  Fig.  71.  The  abdomen  is  long,  slender,  and 
more  or  less  nearly  cylindrical;  the  caudal  end  is  furnished  with 

*  Libellulidae,  Libellula:  libella,  a  water-level,  on  account  of  the  position  of  the  wings 
during  flight. 

\  OdonSta:  odous  (o5ot>?),  a  tooth. 


PSEUDONEUROPTERA.  j\ 

clasping  organs.  The  most  remarkable  peculiarity  of  the  order  is 
the  fact  that  the  copulatory  organs  of  the  male  are  distinct  from  the 
opening  of  the  vasa  deferentia ;  the  former  are  situated  on  the 
second  abdominal  segment,  the  latter  on  the  ninth.  Before  pairing 
the  male  conveys  the  seminal  fluid  to  a  bladder-like  cavity  on  the 
second  abdominal  segment ;  this  is  done  by  bending  the  tip  of  the 
abdomen  forward.  The  pairing  takes  place  during  flight.  The 
male  seizes  the  neck  of  the  female  with  his  anal  clasping  organs ; 
the  female  then  curves  the  end  of  her  abdomen  to  the  organs  on  the 
second  abdominal  segment  of  the  male. 

The  eggs  are  laid  in  water.  In  some  species  the  female  flies 
back  and  forth  over  the  surface  of  the  water,  sweeping  down  at  in- 
tervals to  touch  it  with  the  tip  of  her  abdomen,  and  thus  wash  off 
one  or  more  eggs  into  it.  In  other  cases  the  eggs  are  laid  in  a  mass. 
On  one  occasion,  in  company  with  my  class,  I  saw  a  dragon-fly  pois- 
ing herself  in  the  air  a  short  distance  above  the  point  where  a  water- 
plant  emerged  from  the  water.  At  frequent  intervals  the  insect  de- 
scended with  a  swift  curved  motion,  pushing  the  end  of  her  abdomen 
into  the  water.  On  examination  a  large  cluster  of  eggs  were  found 
attached  to  the  plant  just  below  the  surface.  Professor  Uhler  has 
observed  a  dragon-fly  alight  upon  a  water-plant,  and,  pushing  the 
end  of  her  body  below  the  surface  of  the  water,  glue  a  bunch  of 
eggs  to  the  submerged  stem  or  leaf. 

The  nymphs  of  dragon-flies  (Figs.  68  and  69)  pass  their  lives  in 


FIG.  68.— Nymph  of  Dragon-fly,  Agrioninse.  FIG.  69.— Exuviae  of  nymph  of  Dragon-fly. 

the  water.     They  are  predacious,  feeding  on  such  aquatic  animals 


72  AN  INTRODUCTION   TO  ENTOMOLOGY. 

as  they  can  overcome.  The  form  of  the  body  varies  greatly,  some 
species  being  quite  slender,  while  others  are  nearly  as  broad  as  long. 
These  insects  are,  however,  easily  recognized.  The  general  appear- 
ance of  the  body  is  quite  characteristic  in  spite  of  the  variations  in 
its  proportions.  There  are  also  certain  well-marked  structural  char- 
acters which  distinguish  the  nymphs  of  dragon-flies  from  all  other 
insects.  The  most  available  of  these  characters  is  the  form  of  the 
mouth-parts.  The  mouth  is  furnished  with  well-developed  mandi- 
bles and  maxillae,  all  of  which  are  armed  with  strong  teeth.  But 
none  of  these  is  visible  when  the  insect  is  at  rest.  The  lower  lip  is 
greatly  enlarged,  and  so  formed  that  it  closes  over  the  jaws  conceal- 
ing them.  For  this  reason  it  has  been  termed  the  mask.  But  it  is 
much  more  than  a  mask ;  it  is  a  powerful  weapon  of  offence.  It  is 
greatly  elongated ;  and  is  jointed  in  such  a  way  that  it  can  be  thrust 
out  forward  in  front  of  the  head.  It  is  armed  at  its  extremity 
with  a  pair  of  sharp  hooks,  adapted  for  seizing  and  retaining  its 
prey. 

An  equally  remarkable  peculiarity  of  these  insects  in  their 
nymph  stage  is  the  form  of  the  organs  of  respiration.  The  caudal 
part  of  the  alimentary  canal,  the  rectum,  is  modified  so  as  to  con- 
stitute a  tracheal  gill.  It  is  somewhat  enlarged  ;  and  its  walls  are 
abundantly  supplied  with  tracheae.  Water  is  alternately  taken  in 
and  forced  out  through  the  anal  opening;  by  this  process  the  air  in 
the  tracheae,  with  which  the  walls  of  the  rectum  are  sup- 
plied, is  purified  in  the  same  manner  as  in  an  ordinary 
tracheal  gill. 

In  addition  to  the  rectal  tracheal  gill,  certain  dragon- 
flies  possess  in  their  nymph  stages  other  organs  of  respira- 
tion.    Thus,  in  the  Agrioninae  there  are  leaf-like  caudal 
tracheal  gills  (Figs.  68  and  70) ;  in  some  of  the  Caloptery- 
ginae  we  find  lateral  abdominal  tracheal  gills ;  and  in  cer- 
tain forms  there  are  even  closing  stigmata  on  the  thorax 
.      .  -      and  abdomen. 
Tracheal  j^e  rectai  tracheal  gill  of  immature  dragon-flies  is  an 

SragoS-     organ  of  locomotion,  as  well  as  of  respiration.     By  draw- 
ing water  into  the  rectum    gradually,  and    expelling    it 
forcibly,  the  insect  is  able  to  dart  through  the  water  with  consider- 
able rapidity. 

When  the  nymph  of  a  dragon-fly  is  fully  grown  it  leaves  the 
water  to  transform.  The  skin  of  the  nymph  splits  open  on  the  back 
of  the  thorax  and  head,  and  the  adult  emerges,  leaving  the  empty 


PSE  UDONE  UROPTERA . 


73 


skin  of  the  nymph  clinging  to  the  object  upon  which  the  transfor- 
mation took  place.  Fig.  69  represents  such  a  skin  clinging  to  the 
stem  of  a  water-plant. 

The  dragon-flies  are  predaceous  in  the  adult  as  well  as  in  the 
nymph  state ;  hence  their  vigorous  flight  and  strong  jaws  Tender 
them  formidable  foes  of  less  powerful  insects. 

It  is  not  strange  that  there  should  be  many  popular  superstitions 
regarding  insects  so  conspicuous  as  these.  It  is  a  common  belief 
among  children  that  they  have  the  power  of  sewing  up  the  ears  of 
people,  hence  the  name  darning-needle ;  while  the  negroes  in  the 
Southern  States  believe  that  the  dragon-flies  hover  over  dead  snakes, 
bringing  them  to  life,  and  consequently  call  them  snake-doctors. 

The  Libellulidae  is  a  remarkably  well-defined  group  of  insects. 
The  wings  are  peculiar  in  form  and  venation,  and  especially  in  the 
possession  of  the  nodus ;  the  reproductive  organs  of  the  male  are 
very  distinct  in  form  from  those  of  any  other  insects ;  and  in  the 
nymph  the  structure  of  the  mouth-parts  and  the  organs  of  respira- 
tion are  equally  peculiar.  Owing  to  these  important  differences 
which  exist  between  the  Libellulidas  and  the  most  nearly  allied  in- 
sects, certain  entomologists  regard  the  group  as  an  order,  to  which 
they  apply  the  name  Odonata. 


FIG.  71. — Wing  of  Dragon-fly,  /Eschna.  A,  arc  or  arculus;  aa,  anal  angle;  ac,  antecubital  cross- veins; 
am,  accessory  membrane  or  membranule;  at,  anal  triangle;  da,  basal  area  or  space  ;  c,  c,  costal 
vein  ;  d,  d,  d,  discoidal  areolets  ;  it,  internal  triangle  ;  Is,  lower  sector  of  triangle,  a  prolongation  of 
pco  \  'is',  branch  of  Is  ;  ni,  m,  median  vein  ;  ma,  median  area  or  space  ;  ms,  ms,  median  sector  j  *, 
nodus : 


postcut 

ss,  short  sector ';°2f,"discofdaT'triangle,  usually  termed'  the  tria'ngle  ;  us,  upper  sector  of  the  triangle, 
a  prolongation  of  sttt. 

Figure  71  illustrates  the  nomenclature  of  the  parts  of  the  wing 
in  insects  of  this  order. 


74  AN  INTRODUCTION   TO  ENTOMOLOGY. 


TABLE   OF   SUB-FAMILIES   OF  LIBELLULID^.* 

A.  Wings  alike,  vertically  folded  in  repose.     (Eyes  remote  and  peduncled.) 
B.  Antecubital  cross-veins  numerous,  at  least  five  in  number.     (Wings  al- 
most always  not  petiolated.)  i.  CALOPTERYGIN^E. 
BB.  Antecubital  cross-veins  two  only.     (Wings  always  distinctly  petiolated.) 

2.  AGRIONIN,E. 

AA.  Hind  wings  differently  shaped  from  front  wings  ;    all  four  wings  carried 
horizontally  in  repose. 

B.  Antecubitals  of  the  first  and  second  series  not  corresponding  except  at 

base.     Base  of  second  series  of  postcubitals  with  cross-veins. 

C.  Eyes  remote.  4-  GOMPHIN^E. 

CC.  Eyes  touching  at  a  single  point,  the  touching  part  of  each  forming  an 

acute  angle.  5-  CORDULEGASTERIN^E. 

CCC.  Eyes  touching  for  a  considerable  space,  the  touching  part  straight, 

or  at  a  single  point  (^Eschina  heros),  the  touching  part  rounded  in  a 

single  curve.  3.  ^ESCHIN^E. 

BB.   Antecubitals  of  the  first  and  second  series  corresponding.     Base  of  the 

second  series  of  postcubitals  with  no  cross-veins. 

C.  Each  eye  laterally  tubercled  behind.  6/CoRDULiN^:. 

CC.  Posterior  edge  of  each  eye  simple.  7.  LIBELLULIN^E. 

CALOPTERYGIN^E. — There  are  only  two  genera  of  this  sub-family  repre- 
sented in  our  fauna.  In  Calopteryx  the  wings  are  very  broad,  and  the  basal 
<;pace  has  no  transverse  veins.  Hetarina  differs  in  having  the  wings  rather 
narrow,  and  with  the  basal  space  reticulated.  In  this  genus  the  base  of  the 
wings  in  the  male  is  blood-red. 

AGRIONIN^E. — The  greater  number  of  our  species  belong  to  Lestes  and 
Agrion.  In  Lestes  the  median  and  subnodal  sectors  arise  from  the  principal 
sector  nearer  the  arculus  than  the  nodus ;  while  in  Agrion  these  sectors  arise 
under  the  nodus. 

. — The  greater  number  of  our  species  belong  to  the  typical  genus 
In  the  males  of  this  genus  the  anal  angle  of  the  posterior  wings  is 
acute,  the  lower  anal  appendage  is  usually  triangular,  and  the  second  abdom- 
inal segment  bears  upon  each  side  a  little  ear-like  tubercle.  Of  the  genus 
Anax  we.  have  one  common  species,  A.  junius.  This  is  a  large  insect,  measur- 
ing in  length  68-74  mm.,  and  having  an  alar  expanse  of  104-110  mm.  In  the 
males  of  this  genus  the  anal  angle  of  the  posterior  wings  is  rounded  like  that 
of  the  females;  the  lower  anal  appendage  is  short  and  truncate;  and  the 
second  abdominal  segment  has  not  ear-like  appendages. 

GOMPHIN^E. — In  the  typical  genus  Gomphus  the  triangles  of  all  of  the  wings 
are  without  transverse  veins  ;  this  genus  includes  many  species.  In  the  genera 
to  which  the  following  species  pertain  the  triangles  have  transverse  veins. 
Tachopteryx  thoreyivs  a  large  insect  expanding  100  mm.;  it  is  remarkable  for 
the  length  of  the  pterostigma,  which  measures  9  mm.  Hagenius  brevisfylus  is 
an  even  larger  species,  which  expands  104-1 14  mm.  The  pterostigma  meas- 

*  After  B.  D.  Walsh,  Proc.  Ent.  Soc.  Phil.  II.  p.  259. 


PSEUDONEUROPTERA.  75 

ures  only  6  mm.,  and  the  tarsi  are  very  long.  These  two  species  are  our  most 
common  representatives  of  this  division  of  the  Gomphinae. 

CORDULEGASTERIN^E.— Our  only  genus  is  C or duleg aster,  of  which  but  few 
species  are  found  in  the  United  States. 

CORDULIN^E. — We  have  three  genera  of  this  sub-family,  each  of  which  is 
well  represented  in  our  fauna.  These  are  Macormta,  Epttheca,  and  Cord&lia. 

LiBELLULlN^E. — This  sub-family  is  represented  in  our  fauna  by  at  least  ten 
genera. 

Family  III.— PERLIM;.* 

Order  PLECO'PTERA  of  some  authors.f 

(Stone-flies^) 

The  family  Perlidce  includes  comparatively  few  species  ;  but 
members  of  it  are  common  about  any  of  our  creeks.  These  insects 
are  called  Stone-flies  because  the  immature  forms  are  very  abun- 
dant under  stones  in  the  bed  of  streams.  The  adults  are  found  fly- 
ing about  or  resting  upon  herbage  in  the  vicinity  of  water. 

The  body  is  depressed,  elongated,  and  with  the  sides  nearly  par- 


FIG.  72. — Pteronarcys  regalis. 


allel  (Fig.  72).  The  prothorax  is  large.  The  antennae  are  long, 
tapering,  and  many-jointed.  The  wings  are  unequal,  the  second 
pair  being  the  larger,  and  lie  upon  the  abdomen  when  at  rest.  The 
tarsi  are  three-jointed  ;  and  in  most  species  the  caudal  end  of  the 
abdomen  is  furnished  with  two  setae. 


*  Pedidze,  P6rla:  a  proper  name. 

f  PlecSptera:  pieces  (itXeKoS),  plaited;  pteron  (Ttrepov\  a  wing. 


76 


AN  INTRODUCTION    TO  ENTOMOLOGY. 


FIG.  73. — Nymph  of  Stone-fly, 
Acroneura. 


It  is  easy  to  obtain  the  nymphs  of  these  insects;  by  lifting 
stones  from  the  water  of  swiftly  flowing  streams  the  young  stone-flies 
may  be  found  closely  adhering  to  their  lower 
surface.  They  present  a  wonderfully  flat- 
tened appearance  (Fig.  73) :  the  body  is  de- 
pressed, and  closely  applied  to  the  stone  ; 
while  the  legs,  antennae,  and  caudal  setae  ra- 
diate from  it  on  the  surface  of  the  stone.  In 
our  common  forms  there  is  a  tuft  of  hair- 
like  tracheal  gills  just  behind  the  base  of 
each  leg.  And  the  more  mature  individuals 
present  conspicuous  wing-pads. 

The  nymphs  of  stone-flies  constitute  an 
important  element  in  the  food  of  fishes.  I 
have  found  them  more  often  than  any  other 
insects  in  the  stomachs  of  brook  trout. 

When  about  to  transform  to  the  adult 
state  the  insect  crawls  from  the  water  upon  a 
stone  or  some  other  object.  Their  exuviae 
are  common  in  these  situations.  The  females  of  certain  exotic  spe- 
cies have  been  observed  to  carry  their  eggs  about  with  them, 
attached  in  a  globular  mass  to  the  end  of  the  abdomen,  for  some 
time  before  they  are  laid  in  the  water.  Probably  our  species  pre- 
sent a  similar  habit. 

The  greater  number  of  our  species  belong  to  the  genus  Perla. 
In  this  genus  the  wings  have  but  few  transverse  veins ;  the  anal 
space  of  the  posterior  wings  is  large  and  folded ;  the  palpi  are  bris- 
tle-like ;  and  there  are  two  caudal  setae.  The  genus  Pterondrcys 
(Fig.  68)  is  of  great  scientific  interest,  owing  to  the  presence  of 
tracheal  gills  throughout  the  entire  life  of  the  insects.  The  gills  of 
Pteronarcys  consist  of  little  tufts  of  short  slender  filaments,  of  which 
there  is  a  pair  on  the  ventral  aspect  of  each  thoracic,  and  the  first 
and  second  abdominal  segments.  The  wings  in  this  genus  are 
densely  net-veined. 

There  are  several  species  of  stone-flies  that  appear  in  the  adult 
state  upon  the  snow  on  warm  days  in  the  latter  half  of  winter. 
They  become  more  numerous  in  early  spring,  and  often  find  their 
way  into  our  houses.  The  most  common  one  in  Central  New  York 
is  the  small  snow-fly,  Cdpnia  pygmcea.  It  is  black,  with  gray  hairs. 
The  female  measures  9  mm.  in  length,  and  has  an  expanse  of  wings 
of  1 6  mm.  The  male  measures  only  4^  mm.  (0.18  inch),  and  has 


PSEUDONEUROPTERA.  77 

short    wings   which    extend    only  two-thirds  the  length  of  the  ab- 
domen. 

In  England  certain  stone-flies  are  much  used  by  anglers.  One, 
Chloroperla  viridis,  is  well  known  under  the  name  "  Yellow  Sally,"' 
and  a  species  of  Nemoura  is  called  the  "  Willow-fly.' 


Family  IV.— TERMITID.E.*  ,, 

(Termites,  or  White-ants^ 

The  Termites,  or  white-ants,  are  social  insects,  which  live  in  large 

societies,  consisting  of  several  distinct  forms  of  individuals.     They 

are  chiefly  tropical ;  but  there  is  one  species  which  is  commonly  dis- 

,  tributed  over  the  United  States  east  of  the  Rocky  Mountains ;  and 

several  others  occur  farther  west. 

These  insects  can  be  easily  recognized  by  the  pale  color  of  the 
greater  number  of  individuals  of  which  a  colony  is  composed,  by  the 
fact  of  their  living  in  large  ant-like  colonies,  and  by  the  form  of  the 
abdomen,  which  is  broadly  joined  to  the  thorax  instead  of  being 
pedunculate  as  in  the  ants. 

The  Termites  are  commonly  called  white-ants  on  account  of 
their  color  and  of  a  resemblance  in  form  and  habits  to  the  true  ants. 
These  resemblances,  however,  are  only  very  general.  In  structure 
the  Termites  and  ants  are  widely  separated  ;  as  the  former  are 
among  the  lowest  of  winged  insects,  while  the  latter  stand  near  the 
head  of  the  series.  In  habits  there  is  little  more  in  common  than 
that  both  are  social,  and  the  fact  that  in  each  the  function  of  repro- 
duction is  restricted  to  a  few  individuals,  while  the  greater  number 
differ  in  form  from  the  sexually  mature  males  and  females,  and  are 
specially  adapted  to  the  performance  of  the  labors  of  the  com- 
munity. 

This  development  of  distinct  castes  for  the  performance  of  spe- 
cial functions  is  carried  much  farther  among  the  Termites  than  it  is 
among  the  ants  and  other  social  Hymenoptera.  In  the  latter  there 
are  only  three  forms :  males,  females  or  queens,  and  workers,  which 
are  imperfectly  developed  females.  With  the  Termites  there  are 
nearly  three  times  as  many. 

If  a  white-ants'  nest  be  opened  at  any  season  of  the  year  there 
will  be  found  a  large  number  of  individuals  of  a  dirty-white  color, 

*  TermUidae:    7'ermes,  a  white-ant. 


AN  INTRODUCTION   TO  ENTOMOLOGY. 


FIG.  74. —  Terntesfla- 
•vipes,  worker. 


and  of  the  form  represented  in  Fig.  74.  These  are  named  the 
workers,  for  upon  them  devolve  nearly  all  the  labors 
of  the  colony.  They  may  be  looked  upon  as  indi- 
viduals, whose  physical,  and  especially  sexual,  devel- 
opment has  been  checked  while  yet  nymphae  and 
never  carried  farther.  But  the  development  of  their 
instinctive  powers  is  truly  remarkable ;  for  it  is  this 
caste  that  builds  the  nests,  collects  the  provisions, 
and  cares  for  the  young.  A  study  of  the  internal 
anatomy  of  workers  has  shown  that  both  sexes  are 
represented  in  this  caste ;  the  reproductive  organs 
are,  however,  but  little  developed. 
Associated  with  the  workers,  and  resembling  them  in  color  and 
in  being  wingless,  there  occur  numerous  representatives  of  another 
caste,  which  can  be  recognized  by  the  enormous  size  of  their  heads 
(Fig.  75).  These  are  the  soldiers.  Upon  this  caste 
devolves  the  protection  of  the  colony.  And  they  are 
well  adapted  for  this  work,  their  powerfully  developed 
mandibles  rendering  them  formidable  creatures.  We 
find  among  the  soldiers,  as  among  the  workers,  both 
sexes  represented.  In  some  species  the  male  and 
female  soldiers  differ  externally,  so  that  they  can  be 
distinguished  without  dissection.  But  here,  as  with 
the  workers,  the  reproductive  organs  are  rudimen- 
tary. 

At  a  certain  season  of  the  year,  late  spring 
or  early  summer  for  our  common  species,  there 
can  be  found  in  the  nests  winged  individuals ; 
these  are  the  males  and  females.  These  differ  greatly  in  appear- 
ance from  the  workers  and  soldiers.  In  our  species,  Termes  fld- 
vipes,  they  are  black  or  dark  chestnut  in  color;  the  body  measures 
5  mm.  (0.2  in.)  in  length  ;  while  the  wings  expand  16  mm.  (0.63  in.). 
The  wings  when  not  in  use  are  placed  lengthwise  upon  the  back, 
and  project  more  than  half  their  length  beyond  the  end  of  the  body. 
The  two  pairs  of  wings  are  of  nearly  equal  size,  and  are  furnished 
with  numerous  veins.  In  May  or  June  these  winged  males  and 
females  leave  the  nest  in  a  body.  Sometimes  clouds  of  them  ap- 
pear. After  flying  a  greater  or  less  distance  they  alight  on  the 
ground,  and  then  shed  their  wings.  At  this  time  the  males  seek 
the  females,  seizing  hold  of  them  with  their  mandibles ;  but  it  is 
believed  that  pairing  does  not  take  place  till  a  later  period.  The 


FIG.  75.—  Termes  fla- 
vipes,  soldier. 


PSE  UDONE  UROP  TERA .  jg 

greater  number  of  the  individuals  composing  one  of  these  swarms 
soon  perish.  They  fall  victims  to  birds  and  other  insectivorous 
animals.  But  in  a  few  cases  a  couple  is  taken  in  charge  by  some 
workers;  and  thus  is  founded  a  new  colony.  There  is  usually  at 
the  head  of  a  colony  only  a  single  pair  of  sexual  individuals.  These 
have  been  termed  the  King  and  Queen.  It  should  be  borne  in 
mind,  however,  that  they  are  simply  the  parents  of  the  community ; 
for  all  of  the  individuals  in  a  colony,  except  the  founders  who 
"  elected  "  this  King  and  Queen,  are  their  offspring  ;  and  in  no  case 
among  insects  do  we  find  rulers  at  the  head  of  a  community.  It 
would  have  been  better  in  each  case  had  the  term  Mother  been  ap- 
plied to  the  individual  at  the  head  of  a  colony  of  Termites,  ants,  bees, 
or  wasps  ;  as  the  function  of  such  an  individual  is  merely  the  produc- 
tion of  eggs.  A  cell  is  provided  by  the  worker  Termites  for  their 
King  and  Queen.  This  is  shaped  like  an  inverted 
watch-glass,  and  is  furnished  at  first  with  a  single 
small  opening  ;  later  there  are  several.  Within  this 
cell  the  royal  pair  remain  prisoners  ;  but  they  are 
carefully  attended  by  numerous  workers.  As  the 
eggs  develop  in  the  body  of  the  female  her  abdo- 
men becomes  greatly  extended.  Fig.  76  represents 
such  a  queen,  natural  size.  The  specimen  figured 
is  from  India,  and  was  kindly  given1  to  me  by  Dr. 
Hagen.  The  dark  spots  along  the  middle  of  the 
dorsal  wall  of  the  abdomen  are  the  chitinized  parts 
of  that  region  ;  the  lighter  portions  are  made  up  of 
the  very  much  stretched  membrane  uniting  the 
segments ;  along  each  side  of  the  abdomen  the  spi- 
racles are  visible.  This  specimen  is  a  comparatively 
small  one ;  in  some  species  the  queens  become  six 
or  eight  inches  in  length. 

In  addition  to  the  winged  males  and  females  just 
described,  there  are  sometimes  developed  wingless  sexual  individuals 
which  never  leave  the  nest.  These  are  termed  complemental males  and 
females ;  and  they  serve  as  substitutes  for  the  winged  males  or 
females  whenever  a  community  does  not  find  a  true  king  or  queen. 
The  complemental  females  produce  comparatively  few  eggs,  and 
consequently  never  become  as  large  as  do  the  true  queens.  It  re- 
quires several  of  these  to  replace  a  queen.  Fritz  Mu'ller  found  in 
one  case  a  king  living  in  company  with  thirty-one  complemental 
females.  As  these  wingless  males  and  females  never  leave  the  nest, 


8O  AN  INTRODUCTION    TO   ENTOMOLOGY. 

they  pair  with  their  near  relatives.  The  development  of  winged 
sexual  forms  is  therefore  necessary  in  order  to  provide  for  inter- 
crossing of  individuals  not  closely  related.  Doubtless  here  as  with 
the  true  ants  the  winged  males  and  females  emerge  from  many  nests 
at  the  same  time  and  mingle  in  a  single  swarm :  in  this  way  there  is 
opportunity  for  intercrossing. 

From  the  above  it  can  be  seen  that  among  the  Termites  there 
are  four  distinct  castes :  (i)  Winged  sexual  forms  or  kings  and 
queens;  (2)  Wingless  sexual  forms  or  complemental  males  and 
females  ;  (3)  Workers  ;  (4)  Soldiers.  As  both  sexes  are  represented 
in  each  caste,  we  have  in  all  eight  forms. 

There  is  space  here  for  but  little  regarding  the  habits  of  these 
wonderful  insects.  In  the  tropics  certain  species  build  nests  of  great 
size.  Some  of  these  are  mounds  ten  or  twelve  feet  in  height.  Other 
species  build  large  globular  masses  upon  the  trunks  or  branches  of 
trees.  All  of  the  Termites  are  miners,  and  all  avoid  the  light. 
They  therefore  build  covered  ways  from  their  nests  to  such  places 
as  they  wish  to  visit.  In  some  of  the  hot  countries  they  are  the 
worst  of  all  pests.  They  will  feed  upon  almost  any  organic  matter ; 
they  destroy  wooden  structures  of  all  kinds,  including  buildings  and 
furniture.  Libraries  are  often  completely  ruined  by  them.  In  in- 
festing anything  composed  of  wood  they  usually  eat  out  the  interior, 
leaving  a  thin  film  on  the  outside.  Thus  a  table  may  appear  to  be 
sound,  but  crumble  to  pieces  beneath  a  slight  weight ;  entrance 
having  been  made  through  the  floor  of  the  house  and  the  legs  of  the 
table. 

The  mounds  of  Termites  are  composed  chiefly  of  the  excreted 
undigested  wood  upon  which  the  insects  have  fed.*  This  is  moulded 
into  the  desired  form,  and,  on  drying,  it  becomes  solid. 

Like  other  Pseudoneuroptera,  the  Termites  undergo  an  incom- 
plete metamorphosis.  The  eggs  as  soon  as  they  are  deposited  by 
the  queen  are  carried  away  by  the  workers  to  other  chambers.  The 
young  are  fed  upon  prepared  food,  which  is  stored  up  in  the  form 
of  very  hard  and  tough  rounded  masses,  evidently  composed  of  coin- 
minuted  wood.  It  is  believed  that  the  young  Termites  are  also 
fed  on  the  sclerotia  of  some  fungi.  The  young  white-ants  are  ac- 
tive; and  all  sizes,  from  the  newly-hatched  nymph  to  the  full-grown 

*  That  this  substance  is  composed  largely  of  woody  tissue  is  easily  seen  by  a  micro- 
scopic examination;  and  I  am  informed  by  Prof.  J.  C.  Branner,  who  has  observed  these 
insects  in  Brazil,  that  he  has  seen  the  Termites  eject  the  matter  from  the  caudal  opening 
of  the  alimentary  canal  and  add  it  to  the  nest  or  covered  ways  which  they  were  building. 


PSEUDONEUROPTERA.  8l 

worker,  can  be  found  in  a  nest  at  the  same  time.  At  certain  sea- 
sons  of  the  year  the  nymphs  of  the  kings  and  queens  are  present" 
and  can  be  distinguished  by  their  wing-pads  of  greater  or  less  length! 
Termes  fldvipes  is  common  throughout  the  Eastern  United  States; 
and  it  is  the  only  species  which  occurs  in  this  region.  The  workers 
when  full  grown  measure  about  4  mm.  (0.16  in.)  in  length,  and  are 
of  the  form  shown  in  Fig.  74.  The  soldiers  are  somewhat  larger ; 
one  is  represented  in  Fig.  75.  The  winged  males  and  females 
are  described  above;  they  are  often  found  in  nests  before  they 
have  swarmed  out,  and  swarms  of  them  are  frequently  seen.  But, 
notwithstanding  the  abundance  of  nests  of  this  species,  the  laying 
queen  has  never  been  found.  A  specimen  supposed  to  be  a  queen 
was  collected  in  Florida  by  Mr.  Hubbard,  and  is  in  the  Museum 
of  Comparative  Zoology  at  Cambridge;  but  this  is  believed  by 
Dr.  Hagen  to  be  merely  a  complemental  female. 

Termes  fldvipes  is  not  a  mound-builder.  It  makes  its  nests  in  old 
logs,  in  stumps,  in  the  ground  under  stones  or  other  objects,  and  in 
buildings  or  other  wooden  structures.  It  usually  infests  decaying 
wood  in  the  fields  or  forests ;  but  I  have  known  of  several  instances 
where  it  has  done  serious  injury  to  buildings ;  and  I  have  also  found 
it  infesting  living  plants.  This  habit  of  infesting  growing  plants  is 
manifested  chiefly  in  the  Southern  States;  but  it  has  been  observed 
also  in  New  England.  I  found  the  white-ants  common  throughout 
Florida,  infesting  orange-trees,  guava-bushes,  and  sugar-cane.  In 
this  State  these  insects  are  generally  recognized  as  important  pests. 
They  are  there  known  as  "  wood-lice,"  a  name  whose  use  is  to  be 
deprecated,  as  it  tends  to  create  confusion. 

When  white-ants  infest  living  plants,  they  attack  that  part  which 
is  at  or  just  below  the  surface  of  the  ground.  In  the  case  of  pampas- 
grass  the  base  of  the  stalk  is  hollowed  ;  with  woody  plants,  as 
orange-trees  and  guava-bushes,  the  bark  of  the  base  of  the  trunk  is 
eaten,  and  frequently  the  tree  is  completely  girdled  ;  with  sugar- 
cane the  most  serious  injury  is  the  destruction  of  the  seed  cane. 

The  white-ants  may  be  destroyed  by  water  heated  sufficiently  to 
kill  the  insects  without  injury  to  the  infested  plants.  In  the  case  of 
orange-trees  much  can  be  done  to  prevent  the  attacks  of  these  in- 
sects. My  experience  convinces  me  that  it  is  those  trees  about  the 
crown  of  whose  roots  the  soil  has  been  heaped  that  are  most  liable 
to  become  infested.  It  follows  that  care  should  be  taken  to  remove 
such  soil  immediately  after  each  cultivation  of  the  grove,  leaving  the 
crown,  of  the  roots  exposed.  It  is  also  important  to  remove  all  old 


82  AN  INTRODUCTION   TO  ENTOMOLOGY. 

wood,  especially  pine,  from  near  the  trees;  as  such  wood  is  liable  to 
become  infested,  and  the  white  ants  to  spread  from  it  to  the  orange- 
trees. 

The  zoological  position  of  the  Termitidse  is,  like  that  of  the  Ephemeridae, 
near  the  foot  of  the  insect  series.  In  fact,  the  form  of  the  wings  with  Termes 
is  regarded  as  even  more  primitive  than  that  of  Ephemera;  as  is  also  the 
structure  of  the  thorax,  with  its  equally  developed  and  unusually  distinct  seg- 
ments. But  the  wonderful  development  of  instinctive  powers  and  of  separate 
castes  among  the  white-ants  indicates  that,  although  as  shown  by  their  struc- 
ture, they  represent  one  of  the  lowest  groups  of  winged  insects  preserved  to 
this  time,  they  constitute  the  highest  development  of  their  line.  It  is  a  sug- 
gestive fact  that  Hagen,  who  is  the  best  informed  regarding  the  Termitidse, 
considers  them  closely  related  to  the  Blattidae,  to  which  the  oldest  known  in- 
sects belong. 

Family   V. — PSOCID^E.* 

(Book-lice  et  al.) 

The  best  known  representatives  of  this  family  are  the  minute  in- 
sects common  in  old  papers,  books,  and  neglected  collections ;  and 

which  have  received  the  name  of  Book-lice. 
These  low,  wingless  creatures  form,  how- 
ever, but  a  small  part  of  the  family.  The 
more  typical  and  winged  forms  (Fig.  77) 
bear  a  strong  resemblance  to  plant-lice  or 
Aphides.  The  body  is  oval,  the  head  free, 
and  the  prothorax  is  small.  The  wings 
when  present  are  of  unequal  size,  the  hind 

YiG.jj.—PsPcusvenosus.  .  . 

pair  being  smaller.      When  not  in  use  the 

wings  are  folded  roof-like  over  the  body,  like  those  of  the  Aphides. 
The  tarsi  are  two-  or  three-jointed. 

There  are  two  sub-families,  which  are  distinguished  as  follows : 

A.  Ocelli  wanting;  wings  absent  or  incomplete.  ATROPIISUE. 

AA.  Ocelli  present ;  wings  well  developed.  PSOCIN^:. 

ATROPIN^E. — Two  genera  of  this  sub-family  are  represented  in 
this  country.  In  Atropos  the  wings  are  absent,  the  meso-  and 
metathorax  are  grown  together,  and  the  antennae  are  seventeen- 
jointed.  The  common  Book-louse  is  Atropos  divinatoria.  This  species 
is  about  I  mm.  in  length  ;  it  is  grayish  white,  with  black  eyes.  Closely 
allied  to  this  genus  is  Clothilla,  in  which  the  anterior  wings  are  rep- 
resented by  small  convex  scales ;  the  meso  and  metathorax  are  free, 
and  the  antennae  are  many-jointed. 

*Ps6cidae,  PsOcus  :  psocho  (^oJ^fa),  to  grind. 


PSE  UDONE  UROP  TERA .  8  3 

C.  pulsatoria  is  a  little  more  than  i  mm.  in  length.  It  is  of  a  pale 
yellowish  white,  and  is  found  in  similar  situations  as  the  book-louse. 

PSOCIN^E. — Here  we  find  four  well-developed  wings.  Usually 
these  extend  much  beyond  the  end  of  the  abdomen.  But  short- 
winged  forms  occur  in  species  which  ordinarily  are  long-winged.  Of 
course  the  young  of  all  are  wingless,  and  there  is  a  gradual  develop- 
ment of  the  wings  as  the  insect  matures.  The  antennae  consist  of 
only  thirteen  segments ;  this  will  enable  one  to  separate  the  imma- 
ture forms  from  the  Atropinae. 

The  Psocinse  occur  upon  the  trunks  and  leaves  of  trees,  on  stones, 
walls,  and  palings.  They  feed  upon  lichens,  and  probably  other  dry 
vegetable  matter.  They  are  sometimes  gregarious.  I  have  often 
observed  communities  of  a  hundred  or  more  closely  huddled  together 
on  the  trunks  of  orange-trees  in  Florida,  feeding  upon  lichens. 

The  eggs  are  laid  in  heaps  on  leaves,  branches,  and  bark ;  the 
female  covers  them  with  a  tissue  of  threads.  It  is  believed  that 
both  sexes  have  the  power  of  spinning  threads  similar  to  those  spun 
by  spiders. 

Several  genera  of  Psocinae  occur  in  the  United  States ;  but  the 
greater  number  of  our  species  belong  to  the  genus  Psocus. 

Family  VI.— MALLOPHAGID^* 

Order  MALLOPHAGA  of  some  authors. 

(Bird-lice.) 

The  Mallophdgidce  are  parasites  which  live  on  warm-blooded  ani- 
mals. They  infest  chiefly  birds,  and  on  this  account  the  term  Bird- 
lice  is  applied  to  the  entire  group.  A  few  genera,  however,  are 
parasitic  upon  mammals.  It  is  an  interesting  fact 
that  in  the  case  of  the  genera  that  infest  mammals 
none  of  the  species  are  found  on  birds ;  and  of 
those  that  live  on  birds  none  infest  mammals. 

The  bird-lice  resemble  the  true  lice  in  form, 
being  wingless,  and  with  the  body  more  or  less  flat- 
tened. Certain  species  which  infest  domestic  fowls 
are  well-known  examples.  These  insects  differ  from 
the  true  lice  in  having  biting  mouth-parts.  They 
feed  upon  feathers,  hair,  and  dermal  scales,  while  the  £ul  (From  Law.' 
true  lice  (Family  Pediculidae,  Order  Hemiptera)  have 
sucking  mouth-parts,  feed  upon  blood,  and  infest  only  mammals. 

*  MallSphaga:  mallos  (//aAAdc),  wool;  phagein  (<t>ayeir),  to  eat. 


84  AN  INTRODUCTION    TO   ENTOMOLOGY. 

Menopon  pallidum  is  one  of  the  species  which  infest  the  hen. 
This  is  often  a  pest  in  hen-houses.  It  is  to  free  themselves  from 
this  and  allied  parasites  that  hens  wallow  in  dust  and  scatter  it 
among  their  feathers.  When  fowls  are  confined  so  that  they  cannot 
dust  themselves  they  are  very  liable  to  suffer  from  bird-lice. 

In  order  to  protect  fowls  from  these  pests,  cleanliness  and  the  use 
of  proper  insecticides  are  necessary.  The  house  should  be  thor- 
oughly cleaned  at  least  twice  each  year,  and  the  straw  in  the  nests 
burned.  Sprinkling  powdered  sulphur  in  the  nests,  and  oiling  the 
perches  with  kerosene,  will  do  much  to  keep  the  lice  in  check.  If  a 
house  becomes  badly  .infested  it  should  be  thoroughly  white-washed, 
and  the  fowls  dusted  with  Persian  insect-powder.  Many  writers 
advise  the  use  of  kerosene  upon  infested  fowls. 

There  is  much  doubt  regarding  the  zoological  position  of  the  Mallophaga. 
The  placing  of  them  in  the  Pseudoneuroptera  must  be  regarded  as  a  provi- 
sional arrangement.  They  were  formerly  classed  with  the  true  lice,  but  they  are 
sharply  distinguished  from  them  by  the  structure  of  their  mouth-parts.  Both 
of  these  groups  have  become  so  degraded  as  the  result  of  their  parasitic  habits 
that  it  will  be  very  difficult  if  not  impossible  to  definitely  determine  their 
places  in  the  insect  series.  Certain  German  entomologists  class  together  as 
an  order  the  Termitidae,  Psocidae,  and  Mallophaga  under  the  name  Corrodentta. 
But  this  association  does  not  seem  to  me  natural. 


TABLE  OF  GENERA  OF  MALLOPHAGA. 

A.  Antennae  filiform,  three-  or  five-jointed  ;  maxillary  palpi  invisible. 

B.  Antennae  three-jointed ;  tarsi   with   a  single  claw.     Parasites  on  mam- 
mals, i.  TRICHODECTES. 
BB.  Antennae  five-jointed  ;  tarsi  with  two  claws.     Parasites  on  birds. 
C.  With   movable  appendages  (trabiculae)  on  the  head  in   front  of  the 
antennae  ;  antennae  nearly  alike  in  both  sexes.  2.  DOCOPHORUS. 
CC.  Trabiculae  absent,  or  if  present  not  motile. 
D.  Antennae  filiform,  without  sexual  differences. 
E.  Head  rounded  behind ;  last  segment  in  the  male  rounded  off. 

3.  NIRMUS. 

EE.  Head  abrupt-angled  behind;  abdominal  segments  fused    in  the 
middle.  4.  GONIOCOTES. 

DD.  Antennae  of  male  forcipate  by  a  process  from  the  third  segment. 
E.  Head  angled  behind  ;  terminal  segments  of  female  tubercle-like,  of 
male  rounded  off.  5-    GONIODES. 

EE.^  Head  rounded  behind  ;  terminal  segment  of  male  notched. 

6.  LIPEURUS. 


PSE  UDONE  UROP  TERA .  8  5 

AA.  Antennae  clubbed,  four-jointed  ;  maxillary  palpi  long,  filiform,  four-jointed. 
B.  Tarsi  with  two  claws.     Parasites  on  birds. 

C.   Mesothorax  wanting  ;  antennae  always  concealed. 

D.   Head  very  broad  ;  no  orbital  sinus.  7.   EUREUM 

DD.  Head  elongated,  with  lateral  angles  directed  backwards. 
E.  With  sharply  marked  off  cypleus,  and  shallow  orbital  sinus. 

8.    LjEMOBOTHRIUM. 

EE.  With   only  wavy  head-margins,  and  long  lateral   lobes  on  the 
labrum.  9.  PHYSOSTOMUM. 

CC.  Mesothorax  present. 

D.  Mesothorax  large,  sharply  marked  off ;  head  three-sided ;  antennae 
concealed.  Io.  TRINOTUM. 

DD.  Mesothorax  small,  only  indicated. 

E.  Orbital  sinus  deeps  antennae  usually  elongated  and  visible. 

II.    COLPOCEPHA^UM. 

EE.  Orbital  sinus  very  shallow  or  obsolete,  antennae  concealed. 

12.  MENOPON. 
BB.  Tarsi  with  a  single  claw.     Parasites  on  mammals.  13.  GYROPUS. 

The  following  is  a  list  of  the  described  species  of  the  Mallophaga  which 
infest  domestic  animals  ;  in  each  case  the  host  is  indicated  : 

i.  TRICHODECTES. — Trichodectes  Idtus  (Fig.  79),  dog;  T.  restrains,  cat;  T. 
equi  (Fig.  78),  horse  and  ass;  T.  breviceps,  llama;  T.  climax,  goat;  T.  sphero- 
cephalus  (Fig.  80),  sheep;  T.  scalaris  (Fig.  81),  ox. 


FIG.  79. —  Trichodectes 
latus.     (From  Law.) 


FIG.  80.—  Tricho- 
dectes spheroce- 
phalus.  (From 
Law.) 


FIG.  81.  —  Trichodectes 
scalaris.  (From  Law.) 


FIG.    te.—Goniodes    styliftr. 
(From  Law.) 


2.  DOCOPHORUS. — Docophorus  adustus,  goose  ;  D.  icterodes,  duck. 

3.  NIRMUS. — Ntrmus  clavaformis,   pigeon  ;   N.  numidce,  Guinea-fowl ;   N. 
tesselldtus,  duck. 

4.  GONIOCHOTES. — Goniochotes  compar,   pigeon;   G.   sp.,   Guinea-fowl;  G. 
rectanguldtus,  peacock ;  G.  chrysocephalus,  pheasant ;  G.  hologdster,  hen. 

5.  GONIODES. — Goniodes  numididnus,  Guinea-fowl;   G.  stylifer   (Fig.    82), 


86  AN  INTRODUCTION    TO  ENTOMOLOGY, 

turkey ;  G.  falcicornis,  peacock ;  G.   colchicus,  pheasant ;  G.  disslmilis  and  G. 
gig  as,  hen. 

6.  LlPEURUS. — Lipeiirus  bacillus,  pigeon  ;  L.  polytrapestus,  turkey ;  L.  sp., 
peacock  ;  L.  heterographus  and  L.  varidbilts,  hen  ;  L.  Idcteus  and  L.  jejiinus, 
goose  ;  L.  squdlidus  and  L.  varidbilis,  duck. 

10.  TRINOTUM. —  Trindtum  conspurcdtum  and  T.  squdlidum,  goose  ;   T.  con- 
spur  cdtum,  swan  ;   T.  lilridum,  duck. 

11.  COLPOCEPHALUM. — Colpocephalum  longicaudum,  pigeon;  C.   miniltum, 
swan. 

12.  MENOPON. — Menopon  numidce.  Guinea-fowl;   M.  stramlneum,  turkey; 
M. phacostomum,  peacock;  M.  fuscomaculdtum,  pheasant;  M.  pallidium,  hen. 

13.  GYROPUS. — Gyropus  grdcilis  and  G.  ovdlis,  capybara. 


CHAPTER  VI. 

Order  III.—  ORTHOPTERA.* 

(Cockroaches,  Crickets,  Grasshoppers,  Locusts,  Earwigs,  et  al.) 

The  members  of  this  order  have  four  wings:  the  first  pair  are 
thickened,  and  usually  overlap  when  at  rest ;  the  second  pair  are 
thinner,  and  are  folded  in  plaits  longitudinally.  The  mouth  parts  are 
formed  for  biting.  The  metamorphosis  is  incomplete. 

The  order  Orthoptera  includes  some  of  the  very  common  and 
best  known  insects.  The  most  familiar  representatives  are  the  cock- 
roaches, crickets,  grasshoppers,  locusts,  and  katydids. 

Although  the  song  of  the  katydid  and  the  chirp  of  the  cricket 
are  most  often  associated  with  recollections  of  pleasant  evenings 
spent  in  the  country,  we  cannot  forget  that  to  members  of  this  order 
are  due  some  of  the  most  terrible  insect  scourges  man  has  known. 
The  devastations  caused  by  great  swarms  of  migratory  locusts  are 
not  only  matters  of  historical  record,  but  are  too  painfully  known  to 
many  of  our  own  generation  in  the  Western  States. 

With  the  exception  of  a  single  family  (Mantidae),  the  members  of 
this  order  are  as  a  rule  injurious  to  vegetation.  And  many  species 
are  quite  apt  to  multiply  to  such  an  extent  that  their  destruction  of 
plant  life  becomes  of  economic  importance. 

In  the  Orthoptera  the  two  pairs  of  wings  differ  in  structure. 
The  front  wings  are  leathery  or  parchment-like,  forming  covers  for 
the  more  delicate  hind  wings.  These  wing-covers  have  received  the 
special  name  tegmina.  Excepting  in  the  first  family  (the  earwigs), 
the  tegmina  of  the  Orthoptera  are  thickly  reticulated  with  a  net-work 
of  veins,  and  usually  overlap  at  the  tips.  The  position  and  struc- 
ture of  the  tegmina  differ  in  the  different  families,  and  afford  good 
characters  for  separating  them.  The  more  important  veins  of  the 
tegmina  usually  divide  them  into  three  more  or  less  well-marked 
fields  or  areas.  These  have  been  named,  beginning  with  that  bor- 
dering on  the  front  margin  of  the  wing,  the  costal,  median,  and  anal 
areas,  respectively.  The  hind  legs  are  thickly  netted  with  veins. 

*  OrthSptera:  orthos  (opQo!),  straight;  pteron  (rtrepov),  a  wing. 


88  AN  INTRODUCTION   TO  ENTOMOLOGY. 

The  principal  ones  are  arranged  somewhat  like  the  bars  of  a  fan ; 
and  the  wings  when  not  in  use  are  folded  in  a  fan-like  manner.  The 
name  Orthoptera  is  given  to  this  order  on  account  of  this  longitudi- 
nal folding  and  position  of  the  second  pair  of  wings  when  closed. 

There  are  many  wingless  genera  in  the  order.  A  few  species  have 
the  anterior  pair  only;  and  in  one  instance  at  least, the  first  pair  are 
wanting  while  the  second  pair  are  present. 

The  mouth  parts  are  all  present,  and  are  well  developed.  The 
student  who  wishes  to  get  a  clear  idea  of  the  structure  of  a  typical 
insect's  mouth  cannot  do  better  than  to  dissect  the  mouth  of  a  cock- 
roach or  locust. 

The  appendages  of  the  abdomen  furnish  important  characters  for 

the  purposes  of  classification.  Thus  the 
form  of  the  ovipositor  is  of  great  ser- 
vice  in  distinguishing  the  families ;  and 

t^ie  c^rc^  a  Pa^r  °f  appendages  one  on 
each. .side  near  the  caudal  end  of  the 
abdomen,  are  also  much  used  in  de- 
scriptions. 

In  the  Orthoptera  the  metamorpho- 
sis is  incomplete.  In  the  case  of  those 
species  that  never  acquire  wings  the 
change  in  form  from  the  newly  hatched 
nymph  to  the  adult  is  frequently  in- 
considerable. With  others  we  see  the 
FIG.  83.-Mouth-Parts  of  the  Red-  wings,  developed  by  degrees,  as  de- 
scribed in  Chapter  I.  (Figs.  8  to  13). 

There  are  many  Orthoptera  that  have  in  the  adult  state  only 
rudimentary  wings.  These  resemble  very  strongly  immature  insects. 
It  is  often  important  to  determine  whether  a  short-winged  speci- 
men is  an  adult  or  not ;  this  is  especially  true  in  case  of  the  Acridi- 
dce,  or  locusts.  Fortunately  this  determination  can  easily  be  made 
with  the  Jumping  Orthoptera  (section  Saltatoria).  In  case  of  these 
insects  the  wing-pads  of  the  nymphs  are  inverted,  as  shown  by  the 
curving  down  of  the  extremities  of  the  wing-veins  instead  of  up,  as 
with  the  adult ;  and  the  rudimentary  wings  are  outside  of  the  wing- 
covers,  instead  of  beneath  them.  There  is  also  the  distinction  that 
these  rudiments  of  the  second  pair  of  wings  are  triangular  in  outline, 
and  are  flat,  not  folded  ;  while  the  wings  of  the  adult  are  more  or  less 
folded,  even  when  too  small  to  be  of  use  as  organs  of  flight. 

Certain  species  belonging  to  the  three  higher  families,  Acrididse, 


ORTHOPTERA.  89 

Gryllidae,  and  Locustidae,  are  interesting  on  account  of  the  sounds 
which  they  produce.  A  very  large  proportion  of  the  insect  cries 
heard  in  the  late  summer  and  autumn  come  from  this  source.  The 
organs  by  which  these  notes  are  made  are  chiefly  the  wing-covers. 
It  should  be  remembered  that,  owing  to  their  peculiar  mode  of 
breathing,  insects  have  nothing  that  corresponds  to  our  voice.  It  is 
only  the  males  of  the  Orthoptera  that  sing ;  and  the  musical  appa- 
ratus is  different  in  each  of  the  three  families.  Each  form  will  be 
described  later. 

In  this  connection  perhaps  reference  should  be  made  to  the  sup- 
posed organs  of  hearing  of  these  insects.  In  the  Acrididae  there  is 
on  each  side  of  the  first  abdominal  segment  a  pit,  over  the  mouth  of 
which  is  stretched  a  membrane  :  this  is  termed  the  tympanum,  and  is 
believed  by  some  to  be  an  organ  of  hearing ;  it  is  doubtless  a  sense- 
organ,  but  its  function  has  not  yet  been  determined.  A  pair  of 
similar  organs  occur  near  the  proximal  end  of  each  tibia  of  the  first 
pair  of  legs  in  the  Locustidae  and  Gryllidae. 

The  order  Orthoptera  comprises  seven  families.  These  have 
been  grouped  into  five  sections  by  some  writers ;  and  the  names  of 
the  sections  occur  frequently  in  entomological  works.  Each  of  the 
first  four  sections  includes  only  a  single  family  ;  the  fourth  section 
includes  the  three  remaining  families.  The  names  of  the  sections 
except  the  first  were  suggested  by  the  form  of  the  legs  in  each. 
The  following  are  the  names  of  the  sections  and  the  families  which 
they  include  : 

I.  Dermdptera ;  includes  the  Forficiilidce  or  Earwigs. 
II.  Cursoria  or  Runners ;  includes  the  Bldttid<z  or  Cockroaches. 

III.  Raptoria  or  Graspers;  includes  the  Mdntidce  or  Rear-horses. 

IV.  Ambulatoria  or  Walkers;  includes  the  Phdsmida  or  Walking- 
sticks. 

V.  Saltatoria  or  Jumpers ;  includes  the  Acrldidce  or  Locusts  or 
Short-horned  Grasshoppers,  the  Locustidce  or  Long  horned  Grass 
hoppers  and  Katydids,  and  the  Gryllidce  or  Crickets. 

TABLE  OF   FAMILIES  OF  ORTHOPTERA. 

A.  Posterior  femora  fitted  for  walking,  i.e.,  resembling  those  of  the  other  legs  ; 
ovipositor  with  the  subgenital  plate  concealed  ;  organs  of  flight  of  immature 
forms  in  normal  position  ;  insects  mute. 

B.  Anterior  wings  leathery,  very  short,  without  veins,  meeting  in  a  straight 
line;  posterior  wings  when  present  folded  to  the  middle  of  the  anterior 


9O  AN  INTRODUCTION    TO  ENTOMOLOGY. 

margin;    tarsi  three  jointed,  the  pulvillus  wanting;   cerci  horny,  resem- 
bling forceps.  I.    FORFICULID^E. 
BB.  Anterior  wings  parchment-like,  thickly  veined  ;  posterior  wings  folded 
to  the  base  ;  tarsi  five-jointed  ;  cerci  soft,  jointed  or  without  joints. 
C.  Body  oval,  depressed  ;  head  wholly  or  almost  wholly  withdrawn  beneath 
the    pronotum ;    pronotum    shield-like,    transverse ;    legs    compressed ; 
cerci  jointed  ;  rapidly  running  insects.  2.   BLATTID/E. 
CC.  Body    elongated ;    head    free ;    pronotum   elongated ;    legs    slender, 
rounded  ;  cerci  jointed  or  without  joints  ;  walking  insects. 
D.  Front  legs  fitted  for  grasping;  cerci  jointed.  3.  MANTID.E. 
DD.  Front  legs  simple  ;  cerci  without  joints.                       4.  PHASMID^E. 
A  A.  Posterior  femora  fitted  for  jumping,  i.e.,  very  much  stouter  or  very  much 
longer,  or  both  stouter  and  longer  than  the  middle  femora;  ovipositor  horny, 
free  (except  with  the  mole  crickets);  organs  of  flight  of   immature   forms 
inverted ;  stridulating  insects. 

B.  Antennae  short;  tarsi  three-jointed  ;  supposed  organs  of  hearing  situated 
in  the  first  abdominal  segment;  ovipositor  short,  composed  of  four  sep- 
arate plates;  stridulating  organs  situated  in  hind  femora  and  the  costal 
area  of  the  tegmina.  5.  ACRIDID/E. 

BB.  Antennae  long,  setaceous ;  tarsi  four-  or  three-jointed  ;  supposed  organs 
of  hearing  situated  in  the  anterior  tibiae  and  also  in  the  prosternum ;  ovi- 
positor elongated  (except  in  the  mole  crickets) ;  composed  of  four  connate 
plates. 

C.  Tarsi  four-jointed  ;  ovipositor  (when  exserted)  forming  a  strongly  com- 
pressed, generally  sword-shaped  blade ;  the  stridulating  organs  of  male 
limited  to  the  anal  area  of  the  tegmina.  6.  LOCUSTID^E. 

CC.  Tarsi  three-jointed ;  ovipositor  (when  exserted)  forming  a  nearly 
cylindrical,  straight,  or  occasionally  upcurved  needle ;  the  stridulating 
organs  of  the  male  extend  across  the  anal  and  median  areas  of  the  teg- 
mina. 7.  GRYLLID^:. 


Family  I.— FORFICULID^E.* 
(Earwigs) 

This  family  includes  only  the  earwigs.  With  these  insects  the 
first  pair  of  wings  are  leathery,  very  small, 
without  veins,  and  when  at  rest  meet  in  a 
straight  line  down  the  back,  partially  cov- 
ering the  second  pair  of  wings.  These 
wing-covers  strongly  resemble  those  of  the 
rove-beetles.  The  second  pair  of  wings 

FIG.  84-.-WinK  of  Earwig.      differ  from  those  of  other  Orthoptera  (Fig. 
84).    They  are  furnished  with  radiating  veins 
which  extend  from  a  point  near  the  end  of  the  basal  third  of  the 

*  Forficfllidae:  forficula,  a  pair  of  small  shears. 


ORTHOPTERA,  91 

wing  over  the  distal  part  of  this  organ.  When  the  wing  is  not  in 
use  this  part  is  folded  in  plaits  like  a  fan  ;  and  the  wing  is  folded 
twice  transversely.  With  other  Orthoptera  the  longitudinal  folding 
extends  to  the  base  of  the  wing,  and  there  is  no  transverse  folding. 
The  tarsi  are  three-jointed  ;  and  there  are  no  pulvilli  between  the 
claws.  The  most  striking  character  of  the  family  is  the  form  of  the 
cerci,  which  are  horny,  and  resemble  forceps. 

The  earwigs  are  rare  in  this  country,  especially  in  the  North.  But 
in  Europe  they  are  common,  and  are  often  troublesome  pests. 
They  are  nocturnal,  hiding  in  the  day-time  among  leaves  and  in  all 
kinds  of  crevices,  and  coming  out  by  night.  They  feed  upon  the 
corollas  of  flowers,  fruit,  and  other  vegetable  substances.  When 
troublesome,  they  may  be  trapped  with  hollow  objects  into  which 
they  can  crawl  and  hide  during  the  day-time. 

The  name  of  the  typical  genus,  Forficula, 
is  the  Latin  word  for  scissors.  It  was  sug- 
gested by  the  curious  form  of  the  cerci.  The 
common  name,  earwig,  has  reference  to  a 
widely  spread  fancy  that  these  insects  creep 
into  the  ears  of  sleeping  persons. 

Our  most  common  representative  of  the 
family  is  the  little  earwig,  Ldbia  minor.  This 
is  a  small  species;  the  body  measures  a  little 
less  than  4  mm.  (0.15  inch)  in  length  ;  the  for- 
ceps of  the  male,  1.25-2  mm.  (0.05-0.08  inch); 
and  those  of  the  female  slightly  less.  The 
head  is  blackish ;  the  pronotum  is  narrower 
than  the  head ;  and  the  wings  protrude  be- 
yond the  tips  of  the  tegmina.  FlG-  8s-An  Earwig" 

In  1876  only  13  species  of  this  family  were  known  to  occur  in 
the  United  States.  For  a  tabular  synopsis  of  these  by  S.  H.  Scud- 
der,  see  Psyche,  vol.  I.  p.  177. 

It  is  thought  by  many  entomologists  that  this  family  should 
rank  as  an  order;  and  it  is  so  classed  in  some  of  the  text-books 
under  the  name  Dermdptera,  and  in  others  under  the  name  Euplex- 
optera. 


92  AN  INTRODUCTION    TO  ENTOMOLOGY. 

Family  II. — BLATTID.E.'* 
(Cockroaches^} 

The  cockroaches  are  such  well-known  insects  that  there  is  but 
little  need  for  a  detailed  account  of  their  characteristics.  As  already 
indicated  in  the  table  of  families,  the  body  is  oval  and  depressed  ; 
the  head  is  nearly  horizontal,  and  wholly  or  almost  wholly  withdrawn 
beneath  the  pronotum  ;  the  head  is  bent  so  that  the  mouth  parts 
project  caudad  between  the  bases  of  the  first  pair  of  legs ;  the 
antennae  are  long  and  bristle-like ;  and  the  pronotum  is  shield-like. 
This  family  includes  only  the  cockroaches ;  but  these  insects  are 
known  in  some  localities  as  "  black  beetles,"  and  our  most  common 
species  in  the  Northern  cities  bears  the  name  of  Croton-bug. 

In  the  Northern  States  our  native  species  are  usually  found  in 
the  fields  or  forests  under  sticks,  stones,  or  other  rubbish.  But  cer- 
tain imported  species  become  pests  in  dwellings.  In  the  warmer 
parts  of  the  country,  however,  native  and  foreign  species  alike  swarm 
in  buildings  of  all  kinds,  and  are  very  common  out  of  doors. 

Cockroaches  are  very  general  feeders :  they  destroy  nearly  all 
forms  of  provisions,  and  injure  many  other  kinds  of  merchandise. 
They  often  deface  the  covers  of  cloth-bound  books,  eating  blotches 
upon  them  for  the  sake  of  the  sizing  used  in  their  manufacture;  and 
I  have  had  them  eat  even  the  gum  from  postage-stamps.  They 
thrive  best  in  warm,  damp  situations ;  in  dwellings  they  prefer  the 
kitchens  and  laundries,  and  the  neighborhood  of  steam  and  water 
pipes.  They  are  chiefly  nocturnal  insects.  They  conceal  themselves 
during  the  day  beneath  furniture  or  the  floors,  or  \vithin  the  spaces 
in  the  walls  of  a  house ;  and  at  night  they  emerge  in  search  of  food. 
The  depressed  form  of  their  bodies  enables  them  to  enter  small 
cracks  in  the  floors  or  walls. 

Not  only  are  these  insects  very  destructive  to  our  possessions, 
but  owing  to  their  fetid  odor  merely  the  sight  of  them  awakens  dis- 
gust ;  but  it  is  due  them  to  state  that  they  are  said  to  devour  greedily 
bed-bugs.  This  will  better  enable  us  to  abide  their  presence  in  our 
state-rooms  on  ocean  voyages,  or  in  our  chambers  when  we  are 
forced  to  stop  at  poor  hotels. 

It  is  a  curious  fact  in  the  life-history  of  cockroaches  that  the 
female  lays  all  of  her  eggs  at  once,  they  being  inclosed  in  a  purse- 

*  Blattidae:  bldtta,  a  cockroach. 


!° 


$  1  " 

ORTHOPTERA. 

like  pod  (Fig.  86).     This  pod  varies  in  form  in  different  genera  ;  but 

is  more  or  less  bean-shaped.      Upon  one  edge 

there  is  a  longitudinal  slit.     Within,  the  cap- 

sule is   divided  into   two  spaces,   in    each    of 

which  there  is  a  row  of   separate    chambers,     FlG-  se.-Ootheca  of  a  Cock- 

each  chamber  enclosing  an  egg.     The  females 

carry  this  pod,  or  ootheca,  as  it  is  termed,  about    with    them,  pro- 

truding from  the  end  of  the  abdomen  for  several  days. 

The  use  of  Pyrethrum  or  Persian  insect-powder  is  the  most  effi- 
cient means  of  ridding  an  infested  house  of  these  pests.  It  should 
be  sprinkled  about  their  haunts  at  night,  or  blown  into  the  cracks 
from  which  they  come.  (See  Chapter  XIV.,  Pyrethrum). 

The  Croton-bug  (Bldtta  germdnicd).—  This  is  the  best  known  of  all 
of  the  cockroaches  in  our  Northern  cities.     The  above  popular  name 
originated  in  New  York  City,  and  was  suggested  by  the   fact  that 
these   pests   are  very   abundant,  in  houses,  about  the 
water-pipes    connected    with    the    Croton   Aqueduct. 
The  adult  insect  varies  in  length  from    11   mm.  to  13 
mm.  (0.43  in.  to  0.51  in.).     It  is  light  brown  in  color, 
with  two  longitudinal  black  stripes  on  the  rjronoturn. 
The  wings  extend    beyond  the  tip   of   the   abdomen. 
This    is   an    imported    species,    which    has   spread    to 
nearly  all  parts   of  the  world,  living    upon  ships,    and 
spreading  from  them.     (Fig.  87.) 
FcrotoiTbuhe  ^e   Oriental  Cockroach  (Periplaneta  orientdlis).  — 

This  also  is  a  cosmopolite,  which,  like  the  preceding 
species,  is  a  great  pest  in  dwellings  throughout  the  civilized  world. 
It  is  dark  brown,  and  measures  from  20  mm.  to  23  mm.  (0.8  in.  to  0.9 
in.  in  length).  With  the  females  the  tegmina  are  only  about  4  mm. 
in  length,  and  have  no  wings  under  them.  In  the  males  both  pairs 
of  wings  are  developed,  but  do  not  reach  to  the  end  of  the 
abdomen. 

Of  our  native  species  there  are  two  which  I  have  found  very  com- 
mon at  the  North.  Ectobia  flavoctncta  is  a  blackish-brown  species, 
about  1  6  mm.  (0.63  in.)  in  length,  with  a  light  stripe  extending  on 
each  side  from  the  head  along  the  margin  of  the  pronotum  and  the 
basal  half  of  the  tegmina.  The  wing-covers  do  not  quite  reach  the  tip 
of  the  abdomen.  Platamodes  pennsylvdnica  is  a  much  larger  species, 
with  long  delicate  light-colored  tegmina  and  wings.  These  extend 
beyond  the  tip  of  the  abdomen.  The  margin  of  the  pronotum  is 
light,  while  the  disk  is  dark  ;  and  the  lateral  margins  of  the  tegmina, 
7 


94 


INTRODUCTION   TO  ENTOMOLOGY. 


especially  at  the  base,  are  lighter  than  the  discal  portions.  The 
adult  measures  to  the  tip  of  the  wings  25  mm.  (i 
inch)  or  more.  Although  this  is  a  native  species, 
living  in  our  fields,  it  is  often  found  in  our  dwellings, 
being  attracted  by  lights  at  night. 

Among  our  species  of  cockroaches  are  many 
wingless  forms.  One  of  these  is  represented  in 
Fig.  88. 

Family  III.—  MANTID.E.* 

FIG  ss.-  A  wing-  (^e  Soothsayers  or  Praying  Mantes^ 

less  Cockroach. 

The  members  of  this  family  have  received  many 
popular  names  in  the  regions  where  they  occur,  owing  to  their  gro- 
tesque forms  and  strange  attitudes.  Among  these  are  Rear-horses, 
Race-horses,  Camel-crickets,  Praying  Mantes,  and  Soothsayers.  The 


FIG.  ^g.—Phasmomantis  Carolina. 

species  are  usually  of  considerable  size,  so  that  they  are  conspicuous 
objects.  We  have  no  representative  of  the  family  at  the  North; 
and  there  are  but  few  species  in  our  Southern  States,  they  being 
chiefly  inhabitants  of  tropical  countries. 

The  most  striking  characters  of  these  insects  are  the  great  length 
of  the  prothorax,  it  being  the  longest  segment  of  the  body,  and  the 
enlarged  front  legs,  which  are  fitted  for  grasping.  With  some  spe- 
cies the  wings  resemble  leaves  of  plants  in  form  and  coloring.  This 
resemblance  is  protective,  causing  the  insects  to  resemble  twigs  of 


*  Mantidae,  Mantis:  mantis 
sects. 


,  a  prophet;  also  the  Greek  name  for  these  in- 


ORTHOPTERA. 


95 


the  plants  upon  which  they  are.     All  of  the  species  are  carnivorous. 
/    They  do  not  pursue   their  prey,  but  wait  patiently  with  the  front 
legs  raised  like  uplifted  hands  in  prayer,  until  it  comes  within  reach, 
"when  they   seize  it.      This  position  which  they  as- 
sume   while    waiting    gives    them    most    of    their 
popular    names.      The    eggs   of    the    Mantidae    are 
laid  in  clusters  on  twigs,  and  encased  in  a  flattened 
case   or  ootheca   (Fig.  90).     This   differs    from   the 
ootheca   of   the    cockroach    in    being  composed    of 
hardened  silk. 

The  most  common  species  of  the  Southern 
States  is  Phasmomdntis  Carolina.  This  is  shown 
by  Fig.  89.  By  referring  to  this  figure  the  un- 
usual development  of  the  front  legs  can  be  seen. 
The  parts  of  the  leg  that  are  most  strongly 
spined  are  the  femur  and  tibia  ;  the  slender 
tarsus  appears  as  an  appendage  of  the  tibia ; 
and  the  coxa  is  so  elongated  that  at  first  sight 
it  would  be  mistaken  for  the  femur. 


Family  IV. — 

( Walking-sticks^) 

Even   more   grotesque    in  appearance  than    the 
Mantidae   are    the    insects    constituting    the    family    FlG  Q0  _Egff.masses 
Phasmidae,  and  commonly  known  as  Walking-sticks,      ^fomTif/yT' 
or  Spectres.     They  can  be  easily  recognized  by  their 
long,   linear  bodies,  furnished   with   long  legs  and  antennae.      The 
three  pairs  of  legs  are  similar  in  form.     Their  wings,  when  present, 
are  small,  or  if  large,  very   leaf-like ;  resembling  in  some  instances 
fresh  green  leaves,  in  others,  those  that  are  dry  and  withered.     The 
wingless  species  often  resemble  twigs. 

The  Walking-sticks  are  strictly  herbivorous  ;  they  are  slow  in  their 
motions,  and  often  remain  quiet  for  a  long  time  in  one  place.  Their 
eggs  are  large,  oval,  and  are  scattered  on  the  ground  beneath  the 
plants  upon  which  the  insects  feed,  the  female,  unlike  most  Orthop- 
terous  insects,  making  no  provision  for  their  safety. 

These  insects  are  chiefly  tropical.  Only  a  single  species  is  com- 
mon in  the  Northeastern  United  States.  This  \sDiaphcromcrafe- 


*  Phasmidae,  Phasma:  phasma  (4>d(r/ta),  a  spectre. 


90  AN  INTRODUCTION    TO  ENTOMOLOGY. 

mordta.     It   is  represented   in   Fig.  91,  natural  size.     It   is  a   quite 
common  insect ;  and  on  several  occasions  has  appeared  in  such  great 


FIG.  91. — Diapheromera  femorata.     a,  b,  eggs;  c,  young  hatching.     (From  Riley.) 

numbers  as  to  be  seriously  destructive  to  the  foliage  of  forest  trees. 
Probably  the  best  way  of  destroying  it  when  it  becomes  a  pest  is  to 
spray  the  infested  trees  or  shrubs  with  Paris-green  water,  and  its 


ORTHOPTERA. 


97 


recurrence  should  be  guarded  against  by  burning  the  leaves  upon 
the  ground  under  the  infested  trees  in  the  autumn,  thus  destroying 
the  eggs. 


Family  V.— 
(Locusts  or  Short-horned  Grasshoppers.) 

The  Acrididae  and  the  two  following  families  constitute  the  sec- 
tion Saltatoria  or  Jumpers.  The  members  of  this  section  agree  in 
having  the  hind  legs  fitted  for  jumping,  by  being  either  very  much 
stouter  or  very  much  longer,  or  both  stouter  and  longer,  than  the 
femora  of  the  other  legs.  The  females  are  usually  furnished  with  a 
prominent  ovipositor,  and  the  wings  of  the  immature  forms  are  in 
an  inverted  position. 

In  many  species,  especially  of  the  Acrididse,  the  adult  is  fur- 
nished  with  rudimentary  wings  ;  and  thus  presents  the  appearance  of 
an  immature  form.  But  by  means  of  the  character  just  given  it  is 
easy  to  distinguish  the  adult  even  in  the  case  of  these  short-winged 
species;  for  in  the  immature  forms  the  tegmina  are  folded  beneath 
the  wings,  and  the  principal  veins  of  both  tegmina  and  wings  curve 
downward  instead  of  upward. 

The  family  Acrididce  includes  the  Locusts  or  Short-horned  Grass- 
hoppers. These  are  common  and  well-known  insects.  They  differ 
from  other  Saltatoria  in  having  the  antennae  much  shorter  than  the 
body,  and  consisting  of  not  more  than  twenty-five  segments.  The 
ovipositor  of  the  female  is  short,  and  composed  of  four  separate 
plates,  and  the  basal  segment  of  the  abdomen  is  furnished  on  each 
side  with  a  supposed  organ  of  hearing. 

The  head  is  usually  short,  although  in  two  of  the  sub-families  it  is 
extended  horizontally.  Immediately  under  the  vertex,  but  in  some 
cases  above  it,  there  is  on  each  side  a  little  space  bounded  by  ele- 
vated ridges.  These  spaces  are  termed  the  lateral  foveola  ;  their 
variations  in  form  afford  characters  which  are  much  used  in  classifi- 
cation. The  front  is  generally  traversed  by  three  vertical  keels  or 
carlnce  ;  the  one  on  the  middle  line  is  termed  the  median  carina 
or  frontal  costa,  the  others  are  the  lateral  carlnce.  The  pronotum 
is  divided  into  four  lobes  by  three  more  or  less  well-marked  trans- 
verse sutures  ;  it  is  also  often  furnished  with  a  median  crest.  The 
hind  tibiae  carry  upon  the  upper  side  two  rows  of  spines  :  the  num- 

*  Acrididae,  Acrldium:  acridion  (a.Kpi8iov),  a  small  locust. 


98  AN  INTRODUCTION    TO   ENTOMOLOGY. 

her  of  these  is  of  use  in  distinguishing  species ;  and  the  presence  or 
absence  of  the  last  spine  in  the  outer  row  is  of  much  greater  impor- 
tance. Besides  these  spines  there  are  four  articulated  spurs,  which 
are  situated  in  two  pairs,  one  on  the  outer  and  one  on  the  inner 
side  of  the  tibia.  The  sexes  can  be  easily  distinguished.  In  the 
males  the  ventral  surface  of  the  abdomen  consists  of  nine  segments, 
while  in  the  females  there  are  but  eight.  The  caudal  end  of  the 
body  in  the  females  is  furnished  with  four  horny  appendages,  the 
ovipositor;  in  the  male  the  ventral  pair  of  appendages  is  repre- 
sented by  a  single  plate.  „ 

With  many  species  of  the  Acrididse  we  find  the  males  furnished  with  strid- 
ulating  organs.  These  are  not  nearly  so  highly  developed  as  those  of  mem- 
bers of  the  two  higher  families,  and  are  used  only  in  the  day-time.  The 
Locusts  stridulate  in  two  ways.  Certain  species  rub  the  inner  surface  of  the 
hind  legs  against  the  outer  surface  of  the  wing-covers.  With  these  insects 
there  is  a  thickening  of  one  of  the  main  longitudinal  veins  in  the  centre  of  the 
wing-cover  (vena  radidlts),  and  a  remarkable  extension  of  the  two  areas  be- 
tween this  vein  and  the  costal  margin  of  the  wing-cover  (area  s'capuldris  and 
area  externomedid),  which  serves  as  a  sounding-board,  and  which  is  wanting  in 
the  female.  The  most  common  representatives  of  the  insects  which  stridulate 
in  this  way  belong  to  the  genus  Stenobothrus.  According  to  Scudder,  the 
Stenobothri,  when  about  to  stridulate,  place  themselves  in  a  nearly  horizontal 
position,  with  the  head  a  little  elevated  ;  then  they  raise  both  hind  legs  at 
once,  and  grating  the  femora  against  the  outer  surface  of  the  tegmina,  produce 
notes  which  in  the  different  species  vary  in  rapidity,  number,  and  duration.  The 
first  one  or  two  movements  are  frequently  noiseless  or  faint;  and  when  the 
sky  is  overcast,  the  movements  are  less  rapid.  Scudder  has  recorded  the 
songs  of  several  species  by  means  of  a  musical  notation.* 

The  second  method  of  stridulation  practised  by  locusts  is  by  rubbing 
together  the  upper  surface  of  the  front  edge  of  the  wings  and  the  under  sur- 
face of  the  wing-covers.  Those  which  employ  this  method  stridulate  during 
flight.  Several  common  species  pertaining  to  the  CEdipodinae  will  serve  as 
illustrations  :  Chimarocephala  viridifasctata,  Eucoptolephussordidus,  and  Dissos- 
teria  Carolina.  Certain  other  closely  allied  species  produce  no  sound  whatever. 

Locusts  lay  their  eggs  in  oval  masses,  covered  with  a  tough  glutin- 
ous secretion.  Many  species  deposit  them  in  the  ground,  the  ovi- 
positor of  the  female  being  well  adapted  for  making  the  necessary 
hole.  The  tips  of  the  four  horny  appendages  of  which  it  is  com- 
posed can  be  alternately  applied  together  and  spread  apart ;  in  this 
way  it  is  an  easy  matter  to  force  the  earth  aside  and  press  the  end  of 
the  abdomen  into  the  ground.  Fig.  97  represents  the  Rocky  Moun- 

*  Proc.  Bost.  Soc.  Nat.  Hist.,  vol.  XL 


ORTHOPTERA.  99 

tain  Iccust  in  the  act  of  ovipositing.  Certain  species  make  holes  with 
their  ovipositor  in  a  similar  manner  in  fence-rails,  logs,  stumps,  and 
other  masses  of  wood,  in  which  they  deposit  their  eggs.  After  the 
eggs  are  laid,  the  entrance  to  the  hole  in  the  wood  is  closed  with  a 
little  plug  of  gummy  matter. 

The  transformations  of  three  of  our  more  common  species  of 
Melanoplus  have  been  carefully  studied  by  Riley.*  These  will  serve 
to  illustrate  the  metamorphoses  in  this  family.  In  each  case  there 
are  five  nymph  stages.  In  the  first  of  these  (Fig.  8),  although  the 
insect  would  be  readily  recognized  as  a  young  locust,  there  is  a 
marked  difference  in  the  proportions  of  the  body  from  those  pre- 
sented by  the  adult.  This  is  especially  noticeable  in  the  large  size 
of  the  head,  the  relatively  stouter  thorax  and  hind  femora,  and  in 
the  short  abdomen.  From  this  form  to  that  of  the  adult  there  is 
presented  by  the  other  nymph  stages  a  very  regular  series  of  grada- 
tions. The  most  striking  change  in  the  course  of  the  development 
of  these  insects  is  the  growth  of  the  organs  of  flight.  In  the  first 
nymph  stage  there  is  no  indication  whatever  of  wings ;  in  the 
second  stage  the  caudo-lateral  angles  of  the  mesonotum  and  meta- 
notum  are  very  slightly  prolonged  (Fig.  9).  In  the  third  stage  these 
prolongations  are  more  marked,  and  are  easily  recognized  as  rudimen- 
tary wing-pads  (Fig.  10).  In  the  fourth  stage  a  remarkable  change 
has  occurred  in  these  organs  :  up  to  this  point  they  have  projected 
downward  and  backward ;  they  are  now  turned  up  so  that  what  was 
their  lower  edges  now  meet  on  the  narrow  back,  and  the  side  of 
each  which  was  next  to  the  body  is  now  turned  outward  (Fig.  11). 
While  in  this  position  the  second  pair  of  wing-pads  is  outside  of  the 
first — the  reverse  of  the  relative  positions  of  the  fully  developed 
wings.  In  the  fifth  stage  the  wing-pads  are  longer,  being  now  about 
as  long  as  the  pronotum  (Fig.  12).  Up  to  this  point  the  development 
of  the  wings  has  been  very  gradual,  the  most  pronounced  change  be- 
ing the  reversal  of  these  organs  between  the  third  and  fourth  stages. 
With  the  moult,  which  occurs  at  the  end  of  the  fifth  stage,  the  insect 
assumes  the  adult  form  (Fig.  13).  The  wings  have  now  become 
greatly  elongated  ;  they  are  again  reversed,  so  that  they  assume  the 
primitive  position,  with  the  second  pair  folded  beneath  the  first. 
This  completes  the  changes  through  which  these  organs  pass. 

So  far  as  my  observations  go,  there  is  but  a  single  generation  of 
each  species  of  locust  during  a  year.  In  the  majority  of  cases  at 


See  First  Report  of  the  U.  S.  Ent.  Com.,  Plates  I.,  II.,  and  III. 


IOO  AN  INTRODUCTION   TO  ENTOMOLOGY. 

the  North,  the  species  winters  in  the  egg  state,  and  does  not  become 
fully  developed  till  the  latter  part  of  summer  or  in  the  autumn.  A 
few  adults  survive  the  winter ;  and  we  have  a  few  species  in  which 
the  eggs  hatch  in  the  autumn,  and  the  insects  pass  the  winter  in  the 
nymph  state. 

Many  of  the  Acrididae  never  acquire  fully  developed  wings ;  the 
way  in  which  these  short-winged  adults  can  be  distinguished  from 
nymphs  has  been  given  in  the  generalizations  regarding  the  order. 

The  locusts,  or  grasshoppers  as  they  are  commonly  called,  are  of 
first-class  importance  when  viewed  from  an  economic  standpoint. 
They  feed  on  all  kinds  of  vegetation,  and  they  abound  every  year 
in  all  parts  of  our  country.  Owing  to  their  uniform  abundance, 
they  have  fallen  into  the  category  of  the  commonplace,  and  little  is 
said  about  them.  I  do  not  refer  here  to  the  migratory  species,  the 
incursions  of  which  spread  consternation,  but  to  the  myriads  that 
swarm  in  our  meadows  and  pastures  every  summer  and  autumn. 

Although  the  injuries  caused  by  our  common  locusts  are  very 
great  every  year,  they  are  more  noticeable  in  seasons  of  drought. 
It  frequently  happens  at  such  times  that  every  blade  of  grass  is  con- 
sumed in  extensive  pastures.  This  results  not  merely  from  the 
less  luxuriant  growth  of  the  grass,  but  from  the  fact  also  that  dry 
weather  is  favorable  to  the  development  of  these  insects. 

It  follows  from  the  above  that  such  treatment  of  meadows  and 
pastures  as  shall  best  enable  them  to  withstand  droughts  will  also 
serve  to  protect  them  from  the  ravages  of  locusts.  Thus  the 
presence  in  the  soil  of  a  considerable  amount  of  vegetable  matter, 
furnished  in  the  form  of  stable  manure  or  otherwise,  which  will 
retain  moisture,  will  have  this  tendency :  or  clover  may  be  used  ; 
this  will  shade  the  soil,  and  will  bring  moisture  and  fertility  from 
great  depths  by  means  of  its  long  roots.  In  case  of  heavy  clay 
lands,  tile-draining  has  been  recommended  ;  this  prevents  the  pud- 
dling and  subsequent  baking  and  cracking  of  the  soil  resulting  from 
surface  drainage. 


TABLE  OF  SUB-FAMILIES  OF  ACRIDID^E. 

A.  Pulvilli  present  between  the  claws  of  the  tarsi ;  pronotum  never  extending 
over  the  abdomen. 
B.  Prosternum  unarmed. 

C.  Vertex  and  front  of  head  meeting  at  an  acute  angle;  vertex  extending 
horizontally ;  front  strongly  receding.     (Fig.  92.)  I.  TRYXALIN^:. 


OR  THOP  TERA .  1Ql 

CC.  Head  rounded  at  the  mjion  of  the  vertex  and  front ;  front  perpendic- 
ular, or  nearly  so.     (Fig.  93.) 

D.  The  terminal  spine  of  the  outer  row  of  the  posterior  tibise  wanting 

(Fig.  94,^);  second  abdominal  segment  smooth.          II.  (EDIPODIN^E. 

DD.  The  terminal  spine  of  the  outer  row  of  the  posterior  tibiae  present 

(Fig.  94,  d) ;    second   abdominal   segment  granulated   on   the  sides. 

(Fig-  95-)  III.  EREMOBIN*;. 

BB.   Prosternum  tuberculate,  or  mucronate,  or  produced  into  a  cone. 

C.   Head  rounded  at  the  union  of  the  vertex  and  front ;  front  slightly  re- 
ceding; antennae  filiform.     (Fig.  99.)  IV.  ACRIDIN/E. 
CC.  Vertex  extending  horizontally  in  front  of  the  eyes  ;  front  strongly  re- 
ceding ;  antennae  more  or  less  flattened.     (Fig.  102.)      V.  OPOMALIN^E. 
AA.  No  pulvilli  between  the  claws  of  the  tarsi ;  pronotum  extending  over  the 
abdomen.     (Fig.  103.)                                                                VI.  TETTIGIN^E. 


Sub-family  I.— TRYXALIN.E.* 

In  the  linear  arrangement  of  the  sub-families  of  the  Acrididae 
there  are  placed  first,  i.e.,  lowest,  a  series  of  sub-families  in  which  the 
prosternum  is  unarmed.  The  Tryxalinae  differs  from  the  other 
members  of  this  series  in  that  the  representatives  of  it  have  the  ver- 
tex conical  and  elongated,  the  front  strongly  receding,  and  the  an- 
tennae flattened.  The  antennas  are  inserted  between  the  middle  of 
the  eyes  or  farther  from  the  mouth  than  their  middle ;  the  eyes  are 
usually  longer  than  that  part  of  the  gense  below  them ;  the  posterior 
lobe  of  the  pronotum  is  usually  shorter  than  the  anterior  part ;  the 
median  carina  is  not  at  all  crested ;  and  the  last  spine  of  the  outer 
row  of  the  posterior  tibiae  is  wanting. 

The  characteristic  difference  between  this  family  and  the  next, 
the  CEdipodinae,  is  in  the  joining  of  the  vertex  and  front,  as  indicat- 
ed in  the  table  of  sub-families  given  above.  The  following  species 
will  serve  to  illustrate  the  Tryxalinae : 

Achurum  brempenne. — This  is  one  of  the  most  grotesque  of  all  our 
locusts.  The  body  is  excessively  elongated,  being  almost  linear.  In 
fully  grown  female  specimens  it  measures  more  than  40  mm.  (1.6  in.) 
in  length  ;  and  about  3  mm.  (0.12  in.)  across  in  the  widest  part.  The 
males  are  somewhat  smaller.  The  head  is  greatly  elongated,  and 
ascending;  the  front  is  very  strongly  receding ;  the  antennae  are  a 
little  shorter  than  the  head  and  prothorax,  broad  near  the  base, 
acuminate  at  the  apex,  and  triquetrous.  The  wings  are  smalh 
when  fully  developed  the  tegmina  extend  a  little  beyond  the  third 

*  Tryxalinae,  Tryxalis:  tryxallis  (rpi>£a/\Az'$),  Greek  name  of  these  insects. 


102  AN  INTRODUCTION   TO   ENTOMOLOGY. 

abdominal  segment.     The  color  of  these  insects  is  brown,  sometimes 
marked  with  minute  dark  specks. 

This  species  is  an  excellent  illustration  of  protective  form  and 
coloring.  I  found  it  quite  common  in  Florida  upon  the  "  wire- 
grass  "  which  grows  in  the  sand  among  the  saw-palmettoes ;  and  so 
closely  did  their  brown  linear  bodies  resemble  dry  grass,  that  it  was 
very  difficult  to  perceive  them. 

I  have  also  collected  this  species  near  the  coast  as  far  north  as 
Maryland,  but  have  no  other  information  as  to  its  distribution. 

Among  the  more  common  representatives  of  this  sub-family  in 
the  Eastern  United  States  are  two  species  of  the  genus  Stenoboth- 
rus.  In  each  of  these  there  is  on  each  side  on  the  margin  of  the 
vertex  in  front  of  the  eye  a  little  oblong  pit,  the  lateral  foveolae ; 
and  the  lateral  carinae  of  the  pronotum  are  incurved.  The  more 
common  of  the  two  is  the  Short -winged  Locust,  5.  curtipennis.  In 
this  species  the  lateral  foveolae  are  linear ;  the  tegmina  are  unspotted 
and  of  a  pale  reddish  brown.  In  some  specimens  the  tegmina  and 
wings  are  shorter  than  the  abdomen  ;  in  others  they  are  longer. 
The  males  measure  about  16  mm.  (0.63  inch)  in  length  pthe  females, 
21  mm.  (0.82  inch). 

The  next  species  of  this  genus  in  abundance  is  the  spotted-winged 
locust,  S.  maculipennis.  In  this  species  the  lateral  foveolae  are  shal- 
low, and  broader  towards  the  eye  than  at  the  apex;  the  tegmina  are 
green,  with  a  median  band  of  equidistant  square  black  spots  along 
its  whole  extent ;  sometimes  the  inner  halves  of  the  tegmina  are 
entirely  of  a  rust-red  color.  Both  the  tegmina  and  wings  extend 
beyond  the  tip  of  the  abdomen.  This  species  is  about  the  same 
size  as  the  preceding. 

In  the  genus  Chrysochraon  the  vertex  is  without  foveolae;  and 
the  lateral  carinae  of  the  pronotum  are  nearly  parallel.  One  of  the 
species,  the  Sprinkled  Locust,  C.  conspersum,  is  very  abundant.  It 

is  brown,  with  the  sides  of  the  prono- 
tum and  the  first  two  or  three  abdo- 
minal segments  shining  black  in  the 
male  ;  and  with  the  body  and  teg- 
mina of  the  female  sprinkled  or  mot- 
FIG.  ^.-Chrysochraon  conspersum.  tied  with  darker  brown.  Tht  "egmina 

and  wings  are  a  little   shorter  than 

the  abdomen  in  the  males,  and  much  shorter  in  the  females.  The 
female  is  represented  by  Fig.  92.  The  males  measure  17  mm.  (0.67 
inch)  in  length  ;  the  females,  23  mm.  (0.91  inch). 


ORTHOPTERA, 


Sub-family  II. — 

The  second  of  the  two  more  important  sub-families  in  which  the 
prosternum  is  unarmed,  the  (Edipodince,  includes  genera  in  which 
the  head  is  rounded  at  the  union  of  the  vertex  and  front ;  and  in 
which  the  front  is  perpendicular  or  nearly  so.  The  antennae  are 
linear  or  sub-linear,  and  usually  inserted  nearer  the  mouth  than  the 
middle  of  the  eyes ;  sometimes  they  are  inserted  just  in  front  of  the 
eyes.  The  eyes  are  small  or  of  medium  size ;  rarely  longer  than 
that  part  of  the  cheeks  below  the  eyes. .  The  posterior  lobe  of  the 
pronotum  is  longer  than  the  anterior  part  in  the  typical  forms ;  and 
the  median  carina  is  frequently  entirely  or  partially  crested.  As 
with  the  preceding  sub-family,  the  last  spine  of  the  outer  row  of 
the  posterior  tibiae  is  wanting. 

We  have  many  representatives  of  the  CEdipodinae,  and  these  are 
distributed  by  modern  systematists  among  numerous  genera.  I 
have  selected  a  few  of  the  more  common  species  of  the  Eastern 
United  States  as  illustrations.  These  can  be  separated  by  the  fol- 
lowing table : 

A.  Wings  with  the  disk  yellow. 
B.  Apical  half  of  wing  dusky. 

C.  Dorsal  aspect  of  head  with  a  slight  median  carina,  which  is  quite  prom- 
inent in  the  well-marked   depression  on  the  vertex   (central  foveola). 

Encoptolophus  sordidus. 

CC.  Dorsal  aspect  of  head  without  median  carina,  or  with  merely  an  indi- 
cation of  one;  central  foveola  less  distinct.    Chortophaga  viridifascidta. 
B.  With  a  dark  band  across  the  wings.  Sphardgemon  aqudle. 

AA.  Wings  with  the  disk  black.  Dtssosterta  Carolina. 

AAA.  Wings  with  the  disk  red.  Hippiscus  dtscoideus. 

The  Clouded  Locust,  Encoptolophus  sordidus. —This  species  is 
very  common  in  the  Eastern  Uni- 
ted States  during  the  autumn.  It 
abounds  in  meadows  and  pastures  ; 
and  attracts  attention  by  the 
crackling  sound  made  by  the  males 
during  flight.  It  is  of  a  dirty-brown  FlG  ^,-EncottoiophuS  sordid™. 

color,   mottled    with    spots    of     a 

darker  shade.  It  appears  somewhat  like  the  variety  infuscdta  of  the 
following  species,  but  it  can  be  easily  distinguished  by  the  charac- 
ters given  in  the  table  above.  Size  same  as  following  species. 

*  CEdipodinae,  (Edipoda:  oidos  (oi<5oS),  a  swelling;  pous  (rtovS),  a  foot. 


IO4  AN  INTRODUCTION   TO  ENTOMOLOGY. 

The  Green-striped  Locust,  ChorlopJiaga  viridifascidta. — This  is  a 
very  common  species  from  Maine  to  Florida.  There  are  two  well- 
marked  varieties.  In  one,  the  typical  form,  the  head,  thorax,  and 
femora  are  green,  and  there  is  a  broad  green  stripe  on  each  wing- 
cover,  extending  from  the  horn  to  beyond  the  middle :  this  often  in- 
cludes two  dusky  spots  on  the  edge.  The  second  variety  differs  so 
much  in  appearance,  that  it  was  described  by  Harris  as  a  distinct 
species  under  the  specific  name  infuscdta.  In  this  form  the  ground 
color  is  dusky  brown.  Intergrades  occur,  in  which  the  head  and 
thorax  are  of  a  reddish  velvety  brown.  Length  of  male  to  end  of 
abdomen  20  mm.  (.8  inch),  to  tip  of  wings  25  mm.  (i  inch) ;  length  of 
female  to  tip  of  wings  about  30  mm.  (1.4  inch). 

The  Barren-ground  Locust,  Sphardgemon  cequdle. — This  locust 
occurs  throughout  North  America  east  of  the  Rocky  Mountains. 
In  the  Northern  United  States  it  is  found  during  the  months  of 
July  and  August  on  dry,  barren  hills,  and  on  sandy  plains.  It  is 
ash-gray  in  color,  mottled  with  dusky  brown  and  white  j  the  face  is 
whitish  ;  the  wing-covers  are  marked  with  dusky  bands,  and  are 
semi-transparent  at  tip ;  the  wings  are  traversed  by  a  dark  band  just 
beyond  the  yellow  disk.  Length  to  tip  of  wings,  male,  30  mm. 
(1.2  inch) ;  female,  35  mm.  (1.4  inch). 

The  Carolina  Locust,  Dissosteria  Carolina. — Notwithstanding  its 
specific  name,  this  species  is  common  throughout  the  United  States 
and  Canada.  At  the  North  it  is  the  largest  of  our  common  locusts, 
but  it  is  greatly  surpassed  in  size  by  species  found  in  the  South.  It 
abounds  in  the  highways  and  in  barren  places.  It  takes  flight 
readily,  and  the  males  stridulate  while  in  the  air.  The  color  of  this 
insect  varies  greatly,  simulating  that  of  the  soil  upon  which  it  is  found. 
It  is  usually  of  a  pale  yellowish  or  reddish  brown,  with  small  dusky 
spots.  The  wings  are  black,  with  a  broad,  yellow  margin,  which  is 
covered  with  dusky  spots  at  the  tip.  Length  to  tip  of  wings 
35-45  mm.  (1.4-1.8  inch). 

Hippiscus  discoldeus. — This  is  the  largest  of  our  common  repre- 
sentatives of  the  CEdipodinae.  It  is  a  Southern  species.  I  have, 
however,  specimens  from  as  far  north  as  New  Jersey.  In  color  it  is 
pale  reddish  or  yellowish  brown,  with  dark-brown  spots ;  the  wing- 
covers  marked  with  strongly  contrasting  brown  or  blackish  and  white 
spots  or  bands,  the  anal  area  reddish.  The  disk  of  the  wings  is  red. 
The  body,  especially  of  the  female,  is  heavy,  the  thorax  being  both 
broad  and  deep.  Length  to  tip  of  wings,  male  40  mm.  (1.6  inch); 
female,  55  mm.  (2.2  inch). 


ORTHOPTERA.  IO5 

Sub-family  III. — EREMOBIN^E.* 

This  sub-family  includes  large,  plump  species,  with  the  general 
appearance  of  members  of  the  (Edipodinae.  They  can  be  distin- 
guished from  the  preceding  sub-family  by  the  presence  of  the  ter- 
minal spine  of  the  outer  row  of  the  posterior  tibiae  (Fig.  940)  ;  also 
by  the  presence  of  a  rough  plate  on  the  side  of  the  second  abdominal 
segment  (Fig.  95).  The  vertex  is  usually  broad,  flat,  or  concave,  and 


I 

FIG.  94.— Legs  of  Locusts.  FIG.  95.— First  abdominal  segment  of  Ertmobia. 

strongly  declivous  ;  it  is  then  suddenly  narrowed  and  falls  off  verti- 
cally to  the  plain  of  the  antennae.  In  this  place  it  forms  a  par!  ap- 
parently of  the  frontal  costa,  from  which  it  is  separated  anatomically 
by  a  little  transverse  ridge.  Below  this  ridge  lies  the  middle  ocellus. 
The  eyes  are  relatively  small,  and  widely  separated  by  the  broad 
vertex. 

This  sub-family  is  represented  in  our  fauna  by  Ercmcbia  mdgna 
from  Arizona. 

Sub-family  IV. — ACRIDIN^E. 

Of  the  series  of  sub-families  of  Locusts  in  which  the  prosternum 
is  armed,  representatives  of  but  two  have  as  yet  been  discovered  in 
our  fauna.  To  the  first  of  these,  the  Acridinae,  belong  some  of 
our  most  common  and  at  the  same  time  some  of  the  most  impor- 
tant species.  In  this  sub-family  the  head  is  short,  and  is  rounded 
at  the  union  of  the  vertex  and  front.  The  front  is  slightly  reced- 
ing. The  antennae  are  filiform ;  and  the  terminal  spine  of  the  outer 
row  of  the  posterior  tibiae  is  usually  wanting. 

This  sub-family  is  represented  by  many  forms  in  this  country. 
Only  those  species  that  are  most  likely  to  attract  attention  are  men- 
tioned below.  These  can  be  determined  generically  by  means  of 
the  following  table : 

*  Eremoblnce,  ErimObia:  eremos  (e/a^yuo?),  a  desert;  bioo  (ftiooo),  to  live. 


106  AN  INTRODUCTION   TO  ENTOMOLOGY. 

A.  Wings  as  long  as  or  longer  than  the  abdomen. 

B.  Pronotum  sloping  from  the  median    carina;  lateral  carinae  wanting  ;  ex- 
tremity of  abdomen  in  males  not  swollen.  i.  ACRIDIUM. 
BB.  Pronotum  somewhat  flattened   above;    lateral    margins   angular;    ex- 
tremity of  abdomen  in  the  males  much  swollen.                 4.  MELANOPLUS. 
AA.  Wings  of  adult  shorter  than  the  abdomen  or  wanting. 
B.  Prosternal  spine  prominent. 
C.  Antennae  tapering  to  the  tip ;   and   with  the  segments  very   distinct. 

2.    DlCTYOPHORUS. 

CC.  Antennae  thread-like,  of  nearly  the  same  thickness  throughout ;  seg- 
ments less  distinct.  3.  PEZOTETTIX. 
BB.  Prosternal  spine  slightly  developed.                               5.  BRACHYSTOLA. 

I.  Acrldium. — The  most  common  representatives  of  this  genus 
in  the  Eastern  U.  S.  are  A.  alutdceum  and  A.  rubiginosum.  In  the 
Southern  States  the  most  conspicuous  species  is  A.  americdnum. 

The  Leather-colored  Locust,  Acridium  alutdceum. — This  locust 
is  dirty  brownish  yellow,  with  a  paler  stripe  on  the  top  of  the  head 
and  thorax;  the  wing-covers  are  semi-transparent,  with  irregular  pale- 
brownish  spots,  and  with  the  sutural  margins  yellowish.  Posterior 
margin  of  each  abdominal  segment  with  a  ring  of  black  dots.  The 
wing-covers  are  longer  than  the  abdomen.  Length  of  body  to  end 
of  abdomen,  female  43-50  mm.  (1.7-2  in.),  male  31  mm.  (1.24  in.). 

The  Rusty  Locust,  Acrldium  rubiginosum. — The  color  of  this 
species  is  light  rust-red  ;  the  wing-covers  are  opaque,  rather  paler  on 
the  overlapping  portion  than  elsewhere,  and  sometimes  with  dim 
spots,  but  usually  without  them.  The  wing-covers  are  about  as  long 
as  the  abdomen.  Length  of  female  35-40  mm.  (.4-1.6  in.)  ;  males 
much  smaller. 

The  American  Locust,  Acridium  americdnum. — This  magnificent 


FIG.  96. — Acridium  americanum.     (From  Riley.) 


species  occurs  in  the  Southern  States.     It  can  be  easily  recognized 
from  Fig.  96,  which  represents   its  natural  size.     This  locust  some- 


ORTHOPTERA.  IO; 

times  assumes  the  migratory  habit,  and  is  sometimes  injurious  to 
agriculture. 

2.  Dictyophorus. — This  genus  is  represented  by  a  very  large  and 
clumsy  locust,  which  occurs  in   the  southern  part  of  our  country, 
D.  reticuldtus.     The  adult    is  yellow  and   black ;  the   tegmina  and 
wings  are  shorter  than  the  abdomen  ;  the  base  and  disk  of  the  wings 
are  red,  with  the  outer  margin   black.     Length  of  body  in  female 
about  60  mm.  (2.4  in.),  in  male  50  mm.  (2  in.).     The  nymphs  of  this 
species  differ  remarkably  from  the  perfect  insect,  being  of  a  very  deep 
metallic  bronze-green  color  approaching  black,  marked  with  yellow, 
deepening  into  red  in  spots,  or  wholly  with  blood-red  ;    this  is  most 
conspicuous  in  a  slender  dorsal  stripe  the  whole  length  of  the  crea- 
ture, and  on  the  hinder   edge  of   the    pronotum.     I  found   these 
nymphs  very  ab.undant  in  May  at  Jacksonville,  Fla. 

3.  Pezotettix. — To  the  genus  Pezotettix  belong  a  considerable 
number  of  short-winged  locusts,  of  medium   or  small  size.     More 
than  forty  species  have  been  found  in  the  United  States,  but  nearly 
all  of  these  are  from  the  Far  West  or  from  the  South.     The  mem- 
bers of  this  genus,  according  to   Brunner,  with  but  few  exceptions, 
prefer  cool  and  shady  localities,  and  hence  are  often  found  among 
or  near  rocks,  on  mountain  slopes,  in  clearings  or  on   the  outskirts 
of  timber  belts,  and  in  meadows. 

The  only  species  of  Pezotettix  that  has  been  taken  at  Ithaca  in 
considerable  numbers,/*.  Scudderi,  occurs  among  scattered  trees,  on 
the  crests  and  slopes  of  our  highest  hills.  This  species  can  be  easily 
recognized  by  its  close  resemblance  in  form  and  appearance  to  the 
Common  Red-legged  Locust,  Meldnoplus  femur-nlbrum.  The  only 
conspicuous  difference  is  in  the  organs  of  flight :  in  P.  Scudderi  the 
wing-covers  do  not  extend  beyond  the  second  abdominal  segment. 

In  Pezotettix  glacidlis  the  wings  and  wing-covers  are  wanting. 
This  species  inhabits  the  mountains  of  New  England ;  it  has  also 
been  taken  at  Ithaca,  N.  Y. 

Pezotettix plctus  is  the  brightest  colored  of  all  our  locusts.  It  is 
bluish  green,  with  bright  red  and  yellow  markings,  and  is  found  on 
the  plains  sloping  eastward  from  the  Rocky  Mountains. 

4.  Meldnoplus. — We  have  many  species  of  locusts,  which  belong 
to  this  genus,     Some  of  them   are  among  the  most  common   and 
most    destructive   members   of  the   family  Acridiidae.      Much  has 
been  written  concerning  them  ;  but  as  most  writers  have  believed 
that  they  belong  to  the  genus  Caloptenus,  it  will  be  necessary  to 


IO8  AN  INTRODUCTION   TO  ENTOMOLOGY. 

look  under  that  head  in  the  older  works  for  descriptions  of  them.* 
The  following  table  will  aid  in  determining  the  males  of  the  species 
mentioned  below  ;  as  a  rule  there  will  be  but  little,  if  any,  trouble 
in  assorting  the  females  after  the  males  are  determined. 

A.  Apex  of   last   abdominal    segment  of  male  distinctly  notched. 
B.  Length  of  body  to  tip  of  wing-covers  29-35  mm-  (1.16-1.4  inches). 

M.  SPRETUS. 
BB.  Length  of  body  to  tip  of  wing-covers  23-26  mm.  (0.9-1.04  inches). 

M.    ATLANTIS. 

AA.  Apex  of  last  abdominal  segment  of  male  entire  or  most  obscurely  notched. 
B.  Anal  cerci  enlarged  at  apex.  M.  FEMORATUS. 

BB.  Anal  cerci  tapering. 
C.  Species  of  medium  size  ;  anal  cerci  much  narrowed,  but  without  a  notch. 

M.  FEMUR-RUBRUM. 

CC.  Species  of  large  size  ;  anal  cerci  suddenly  narrowed,  making  a  prom- 
inent right-angled  notch  on  lower  side.  M.  DIFFERENTIALS. 

The  Rocky  Mountain  Locust  or  Western  Grasshopper,  Meldnoplus 
spretus. — The  most  terrible  of  insect  scourges  that  this-country  has 
known  have  been  the  invasions  of  this  species.  Large  areas  of 


FIG.  97.— Egg-laying  of  the  Rocky  Mountain  Locust,  a,  a,  a,  female  in  different  positions,  oviposit- 
ing ;  b,  egg-pod  extracted  from  the  ground,  with  the  end  broken  open  ;  c,  a  few  eggs  lying  loose 
on  the  ground  ;  de  shows  the  earth  partially  removed,  to  illustrate  an  egg-mass  already  in  place, 
and  one  being  placed  ;  /shows  where  such  a  mass  has  been  covered  up.  (From  RUey.) 

country  have  been  devastated,  and  the  inhabitants  reduced  to  a 
state  of  starvation.  The  cause  of  all  this  suffering  is  not  a  large 
insect.  It  is  represented  natural  size  by  Fig.  97.  It  measures  to 

*  For  a  statement  of  the  reasons  for  the  adoption   of  the  name  Melanoplus,  see 
paper  by  S.  H.  Scudder,  Proc.  Boston  Soc.  Nat.  Hist.,  Vol.  XIX.  p.  261. 


OR  7  HOP  TERA .  !  QQ 

the  tip  of  its  wing-covers  29-35  mm.  (1.16-1.4  inches),  and  resembles 
very  closely  our  common  Red-legged  Locust,  the  most  abundant  of 
all  our  species.  It  can  easily  be  distinguished  from  this  species  by 
the  greater  length  of  the  wings,  which  extend  about  one  third  of 
their  length  beyond  the  tip  of  the  abdomen,  and  by  the  fact  that 
the  apex  of  the  last  abdominal  segment  in  the  males  is  distinctly 
notched. 

The  permanent  home  or  breeding  grounds  of  this  species  is  in 
the  high  dry  lands  on  the  eastern  slope  of  the  Rocky  Mountains, 
extending  from  the  southern  limit  of  the  true  forests  in  British 
America  south  through  Montana,  Wyoming,  the  western  part  of 
Dakota,  and  the  Parks  of  Colorado.  There  are  also  regions  in  which 
the  species  exists  permanently  west  of  the  Rocky  Mountains  in 
Idaho  and  Utah, 

When  the  food  of  this  insect  becomes  scarce  in  its  mountain 
home,  it  migrates  to  lower  and  more  fertile  regions.  Its  long  wings 
enable  it  to  travel  great  distances ;  and  thus  the  larger  part  of  the 
region  west  of  the  Mississippi  River  is  liable  to  be  invaded  by  it. 
Fortunately,  the  species  cannot  long  survive  in  the  low,  moist  regions 
of  the  valleys.  Although  the  hordes  of  locusts  which  reach  these 
sections  retain  their  vigor,  and  frequently  consume  every  bit  of 
green  vegetation,  the  young,  which  hatch  from  the  eggs  that  they 
lay,  perish  before  reaching  maturity.  In  this  way,  the  invaded 
region  is  freed  from  the  pest  until  it  is  stocked  again  by  another 
incursion.  There  is,  however,  a  large  section  of  country  lying 
immediately  east  of  the  great  area  indicated  above  as  the  permanent 
home  of  this  species,  which  it  frequently  invades,  and  in  which  it  can 
perpetuate  itself  for  several  years,  but  from  which  it  in  time  dis- 
appears. This  sub-permanent  region,  as  it  has  been  termed,  extends 
east  in  British  America  so  as  to  include  nearly  one  third  of  Manitoba ; 
and,  in  the  United  States,  it  embraces  nearly  the  whole  of  Dakota, 
the  western  half  of  Nebraska,  and  the  north-east  fourth  of  Colorado. 

The  temporary  region,  or  that  only  periodically  visited  and  from 
which  the  species  generally  disappears  within  a  year,  extends  east 
and  south  so  as  to  include  more  than  half  of  Minnesota  and  Iowa, 
the  western  tier  of  counties  of  Missouri,  the  whole  of  Kansas  and 
Indian  Territory,  and  the  greater  part  of  Texas.  The  country  lying 
east  of  the  section  thus  indicated  has  never  been  invaded  by  this 
locust,  and  there  is  no  probability  that  it  will  ever  be  reached  by  it. 

The    United    States  Entomological  Commission  has  published 


IIO 


AN  INTRODUCTION   TO  ENTOMOLOGY. 


three  large  volumes  regarding  this  insect.     The  student  is  referred 
to  them  for  a  detailed  account  of  it. 

The  Lesser  Locust,  Meldnoplus  atldntis. — This  is  a  common 
species,  which  is  very  closely  allied  to  the  Rocky  Mountain  Locust. 
It  can  be  distinguished,  however,  by  its  smaller  size,  as  indicated 
above,  and  by  its  shorter  wings.  The  specific  name  is  an  inappro- 
priate one ;  for  the  species  occurs,  throughout  at  least  the  northern 
part  of  our  country,  from  the  Atlantic  to  the  Pacific. 

The  Red-legged  Locust,  Meldnoplus  femur-rubrum. — This  is  the 
most  familiar  member  of  the  family  Acridiidae  throughout  the 
United  States,  except  where  M.  spretus  occurs.  It  is  more  abundant 

than  any  other  locust  east  of  the  Missis- 
sippi ;  it  is  this  and  the  preceding  species, 
which  is  usually  confounded  with  it,  that 
ravage  our  meadows  and  pastures  more 
than  all  other  species  combined.  The 
female  is  represented  natural  size  by  Fig. 

98. 

Meldnoplus   femoratus. — This    species    also    extends   from   the 


FIG.  98. — Melanoplus  femur-ru- 
brunt. 


FIG.  99. — M.  femoratus.     (From  Riley.) 

Atlantic  to  the  Pacific.  It  is  the  largest  representative  of  the  genus 
that  occurs  in  the  Eastern  States.  It  is  marked  with  a  yellowish 
stripe,  extending  along  each  side  from  the  upper  angle  of  the  eye  to 
the  tip  of  the  elytra  (Fig.  99).  The  length  of  the  body  to  the  tip 


FIG.  zoo.— M.  dijtferentialis.     (From  Riley.) 


of  the  abdomen  varies  from  25  mm.  (i  inch)  to  40  mm.  (1.6  inches). 
This  species  has  been  confounded  in  most  of  our  works  on  Ento- 


ORTHOPTERA. 


Ill 


mology  with  M.  bivittatus,  a  closely  allied  species,  which  occurs  in 
the  interior. 

M.  differ  entidlis.  —  This  species  is  slight- 
ly larger  than  the  preceding  ;  it  lacks  the 
prominent  yellow  stripes,  and  is  confined 
to  the  central  portion  of  the  United  States 
(Fig.  100). 

5.  Brachystola.  —  This  genus  is  repre- 
sented by  the  "  Lubber  Grasshopper"  or 
Clumsy  Locust  of  the  plains,  B.  mdgna. 
This  insect  is  confined  to  the  central 
portion  of  North  America,  and  it  can  be 
readily  recognized  by  the  accompanying 
figure  (Fig.  101). 


Sub-Family  V.  — 

This  sub-family  is  closely  related  to  the 
Acrididae  ;  and  the  members  of  it  resemble 
that  sub-family  in  having  the  prosternum 
armed.  The  Opomalinae  are  distinguished 
by  the  vertex  extending  horizontally  in 
front  of  the  eyes,  by  the  strongly  receding 
front,  and  by  the  short  fore  and  middle  femora.  The  antennae  are 
usually  more  or  less  flattened  ;  and  the  terminal  spine  of  the  outer 
row  of  the  posterior  tibiae  is  never  wanting. 

Several  genera  of  this  sub-family  are  represented  in  this  country. 
The  species  are  more  common  in  the  South  and  West  than  in  the 


FIG.  101. — Brachystola  mngna. 
(From  Riley.) 


FIG.  102.  —  Leptysma  marginicolle. 


Northeast.     Fig.  102  represents  Leptysma  marginicolle  ;  this  species 
occurs  in  Florida,  and  will  serve  as  an  illustration  of  the  sub-family. 


Sub-Family  VI.— 

The  Tettigince  includes  small  locusts  of  very  unusual  form.    The 
most  striking  character  of  the  sub-family  is  the  shape  of  the  pro- 


*OpomalInse,  Opomala:  ops  (00$},  appearance;  omalos  (o^nrAoS),  plane. 
f  Tettiglna,  Tgttix:  tettix  (r£rrz|),  the  Greek  name  for  these  insects. 


112  AN  INTRODUCTION   TO  ENTOMOLOGY. 

notum.       This   is    prolonged  backwards  over  the   abdomen   to   or 
beyond    its  extremity  (Fig.  103).     The   head  is  deeply  set   in  the 
pronotum,  and  the  prosternum  is  expanded  into 
a  broad  border  which  partially  envelops  the  mouth 
like  a  muffler.     The  antennae  are  very  slender  and 
FIG  io3—  Tetttx        short.    The  tegmina  are  rudimentary,  being  in  the 
form  of  small,  rough  scales,  while  the  wings  are  usu- 
ally well  developed.     These   locusts  differ,  also,  from    all  others  in 
having  no  pulvilli  between  the  claws  of  the  tarsi. 

The  Tettiginae  are  commonly  found  in  low,  wet  places,  and  on 
the  borders  of  streams.  Their  colors  are  usually  dark,  and  are  often 
protective,  closely  resembling  that  of  the  soil  upon  which  the  insects 
occur.  They  are  very  active,  and  possess  great  leaping  powers. 

Three  genera  of  this  sub-family  are  represented  in  this  country. 
These  can  be  separated  by  the  following  table : 

A.  Pronotum  arched  roundly,  antennae  12-jointed.  BATRACHIDEA. 
AA.  Pronotum  nearly  or  quite  horizontal. 

B.  Antennae  13-  or  14-jointed.  TETTIX. 

BB.  Antennae  22-jointed.  TETTIGIDEA. 

Family  VI.— LOCUSTID^E.* 
(Long-horned  Grasshoppers  and  Katydids^) 

The  members  of  this  family  are  easily  recognized.  They  differ 
from  the  Acrididae  in  the  great  length  of  the  antennae,  which  are 
longer  than  the  body.  From  the  Gryllidae,  which  they  resemble  in 
the  length  of  the  antennae,  they  are  distinguished  by  the  form  of  the 
ovipositor,  which  is  compressed  and  sword-shaped  ;  and  by  the  four- 
jointed  tarsi.  As  with  the  Crickets,  the  tegmina  of  the  males  are 
furnished  with  a  musical  apparatus.  But  this  occupies  a  much 
smaller  part  of  the  tegmina  than  with  the  Crickets.  Excepting  this 
small  area,  the  anal,  the  tegmina,  when  at  rest,  are  vertical. 

The  name  of  this  family,  as  is  the  custom,  is  derived  from  the 
name  of  its  typical  genus,  Locusta.  But  the  insects  which  are  rightly 
termed  in  popular  language  Locusts  belong  to  the  preceding  family, 
the  Acrididae.  That  is,  to  that  family  belong  the  insects  spoken  of 
in  the  Bible,  and  in  modern  European  works,  as  locusts.  In  this 
country,  unfortunately,  the  term  grasshopper  has  been  used  to  in- 
clude both  the  true  grasshoppers,  i.e.,  the  Locustidae,  and  the  true 
locusts:  while  the  term  locust  has  been  applied  to  an  insect  of  an- 

*  Locftstidae,  Locusta:   Locusta,  a  locust. 


ORTHOPTERA.  \\<$ 

other  order,  the  Cicada.  In  order  to  avoid  confusion,  I  have  referred 
to  the  members  of  the  Locustidae  and  the  Acridiidae  as  Long-horned 
Grasshoppers  and  Short-horned  Grasshoppers  respectively.  It  is 
better,  however,  to  call  the  former  Grasshoppers,  and  the  latter  Lo- 
custs. This  last  term  should  never  be  applied  to  the  well-known 
insect  which  appears  once  in  seventeen  years ;  this  is  rightly  called 
the  Periodical  Cicada. 

Representatives  of  each  of  the  more  common  genera  of  the  North- 
eastern United  States  are  mentioned  below.  These  genera  can  be 
separated  by  the  following  table  :* 

A.  Wingless,  or  with  rudimentary  wings  and  wing-covers. 
B.  Pronotum  not  extended  over  the  meso-  and  metanotum. 

i.  CEUTHOPHILUS. 

BB.  Pronotum  extended  over  meso- and  metanotum.        9.  THYREONOTUS. 
AA.  Winged. 

B.  Tegmina  expanded  in  the  middle. 

C.  Tegmina  much  broadened  in  the  middle,  concave.    5.  CYRTOPHYLLUS. 
CC.  Tegmina  somewhat  broadened  in  the  middle,  not  concave. 

D.  Ovipositor  very  small.  7.  MICROCENTRUM. 

DD.  Ovipositor  of  medium  size.  6.  AMBLYCORPHYA. 

BB.  Tegmina  not  expanded  in  the  middle. 
C.  Vertex  of  the  head  with  a  conical  projection  forwards. 

4.    CONOCEPHALUS. 

CC.  Vertex  of  the  head  without  a  conical  projection. 

D.  Ovipositor  straight,  or  very  nearly  so;  insect  small.     2.  XIPHIDIUM. 
DD.  Ovipositor  curved  ;  insect  large. 

E.  Ovipositor  curved  sharply  upwards.  8.  SCUDDERIA. 

EE.  Ovipositor  sword-shaped.  3.  ORCHELIMUM. 

In  order  to  facilitate  the  study  of  the  Locustarians,  our  common 
genera  can  be  arranged  in  four  groups ;  namely,  the  Cricket-like 
Grasshoppers,  the  Meadow  Grasshoppers,  the  Katydids,  and  the 
Shield-backed  Grasshoppers. 

I.   The  Cricket-like  Grasshoppers. 

i.  Ceuthophilus. — To  the  genus  Ceuthophilus  belong  certain 
wingless  grasshoppers,  which  bear  some  resemblance  in  form  to 
crickets  (Fig.  104).  They  have  a  short,  thick  body  and  remarkably 
stout  hind  femora,  like  a  cricket,  but  are  entirely  destitute  of  teg- 
mina  and  wings.  All  the  species  in  our  collection  are  either  of  a 
pale  brown  or  dirty  white  color  and  more  or  less  mottled  with  either 

*  After  S.  H.  Scudder,  Boston  Journal  Natural  History,  Vol.  VII.  p.  414- 


114  AN  INTRODUCTION   TO  ENTOMOLOGY. 

lighter  or  darker  shades.     These  insects  are  found  under  stones  and 

rubbish  in  woods.  Very  closely  al- 
lied to  them  are  the  "  Cave-crick- 
ets." These  belong  to  the  genus 
Haden&cus*  H.  caverndrum  inhabits 
the  caves  of  this  country;  it  has  very 
FIG.  T.Qit.—Ceuthophiius,  long  legs  and  antennae,  is  colorless 

and  blind. 

II.   The  Meadow  Grasshoppers. 

2.  Xiphldium. — From  the  middle  of  the  summer  to  the  autumn 
there  may  be  found  upon  the  grass  in  our  meadows  and  moist  pas- 
tures many  light-green  grasshoppers  of  various  sizes.     These,  on  ac- 
count of  the  situations  in  which  they  are  usually  found,  are  termed 
the  meadow  grasshoppers.     A  large  proportion  of  the  species  belong 
to  the  genus  Xiphidium.     This  genus  comprises  the  smaller  of  our 
common  species.      The  members  of  it  do  not  have  the  head  fur- 
nished with  a  conical  projection,  and  the  ovipositor  of  the  females 
is  straight  and  sword-shaped    (Fig.    105). 

We  have x  three    common    species    in  the 
Middle  States.     In  one  of  them,  X.  fas- 
datum,  the  tegmina  and  wings  are  long, 
extending  far  beyond  the  tip  of  the   ab- 
domen.     In    each  of   the   other    species 
the  tegmina  and  wings  are    much    short- 
ened.     X.    ensifer   is    characterized  by   the    great   length    of    the 
ovipositor,  which   is  longer  than  the  rest  of  the  body ;    while  the 
ovipositor  of  X.  brevipennis  is  a  little  shorter  than  the  hind  femora. 

3.  Orchellmum. — These  insects  differ   from   the   other  common 
meadow  grasshoppers  in  having  the  ovipositor  curved.     Our  most 
common  species  is  O.  vulgdre.     This  species  measures  from  the  ver- 
tex of  the  head  to  the  end  of  the  abdomen  18  mm.  (0.7  inch),  or  to 
the  tip  of  the  wing-covers  25  mm.  (i  inch).     The  brown  line  on  the 
dorsal  aspect  of  the  head  and  thorax  does  not  extend  down  upon 
the  front  of  the  head ;  in  the  males  there  are  two  short  black  dashes 
on  each  of  the  tegmina  ;  the  four  form  the  angles  of  a  square,  inclos- 
ing the  musical  apparatus.     The  wings  equal  the  tegmina  in  length 
or  are  a  little  shorter.     Another  common  species  is  O.  glabcrrimum. 
This  has  the  dorsal  band   and  the  musical  apparatus  of  the  males 
bordered  with  black,  and  the   ovipositor  slightly  expanded   in  the 
middle.     O.  agile  has  a  narrow  dark  streak  down  the  middle  of  the 


ORTHOPTERA.  H5 

front  of  the  head.  O.  condnnum  is  found  in  Massachusetts ;  this 
also  has  a  dark  streak  extending  down  the  front  to  the  labrum,  but 
it  expands  broadly  in  the  middle  of  the  face. 

4.  Conoccphalus. — This  genus  includes  the  largest  of  our  meadow 
grasshoppers.     It  differs  from  the  genera  already  named  in  having 
the  head  prolonged  into  a  cone-shaped  projection.     The  species  are 
found  in  trees  as  well  as  in  grass,  having  a  strong  resemblance  to  the 
katydids  both  in  appearance  and  habits.     The  most  common  species 
throughout  the  eastern  part  of  our  country  is  C.  ensiger.     Both  sexes 
have  very  long  wings ;  and  the  ovipositor  of  the  female  is  remarka- 
ble for  its  length.     The  length  of  the  body  from  the  tip  of  the  head 
to  the  end  of  the  abdomen  is  30  mm.  (1.2  inches),  while  the  distance 
from  the  tip  of  the  head  to  the  end  of  the  wings  or  ovipositor  is  twice 
that  amount.     ,Two  distinct  forms  of  this  species  occur;  one  is  pea- 
green,  and  the  other  is  of  a  brownish  straw  color.     C.  robiistus  is  a 
stouter  species  than  the   preceding,  and    has  a  shorter  ovipositor. 
This  also  exhibits  dimorphism,  being  either  pea-green  or  brown  in 
color.     The  specimens  in  our  collection  are  from  Cape  Cod  and  New 
Jersey.     I  have  not  seen  any  notice  of  its  occurring  in  the  interior. 

III.   The  Katydids. 

The  song  of  the  Katydids  is  known  to  every  lover  of  Nature 
that  lives  in  the  country.  But  the  insects  themselves  are  much  less 
familiar.  Only  the  careful  and  patient  observer  succeeds  in  tracing 
the  well-known  and  oft-repeated  "  Katy-did,  Katy-did  "  or  "  Katy- 
she-did  "  to  its  source.  The  successful  ones  are  rewarded  by  the 
sight  of  a  beautiful  insect.  The  Katydids,  of  which  there  are  in  the 
United  States  at  least  a  dozen  species,  are  large  green  grasshop- 
pers with  broad,  leaf-like  wing-covers  and  long,  delicate  antennae. 
They  differ  from  the  meadow  grasshoppers  in  being  arboreal. 
They  are  protected  from  observation  by  the  color  and  shape  of  their 
tegmina,  which  resemble  the  leaves  of  trees.  Although  they  feed 
upon  the  foliage  of  the  trees  which  they  inhabit,  it  is  rare  that  they 
are  sufficiently  abundant  to  be  of  economic  importance.  The  only 
locality  in  which  I  have  known  them  to  be  injurious  is  Florida, 
where  they  infest  orange-trees. 

Our  species  represent  four  genera.  These  can  be  separated  by 
the  table  given  above. 

5.  Cyrtophyllus.—1\&  true   Katydid,  the  one  whose  song  sug- 
gested the  popular  name,  is  Cyrtophyllus  concdvus.     This  has  been 


Il6  AN  INTRODUCTION   TO  ENTOMOLOGY. 

named  the  Broad-winged  Katydid  ;  it  occurs  throughout  the  Central 
and  Eastern  States.  A  closely  allied  species,  C.  perspicilldtus,  occurs 
'in  the  South.  These  differ  from  other  Katydids  in  having  the 
wings  shorter  than  the  tegmina,  and  in  having  the  tegmina  very  con- 
vex, so  that  the  insects  have  an  inflated  appearance,  instead  of  a 
narrow,  compressed  form,  as  is  usually  the  case.  The  Southern  spe- 
cies has  shorter  tegmina,  more  robust  legs,  and  the  musical  appara- 
tus of  the  male  is  slightly  broader  than  in  the  Northern  form. 

6.  Amblycorypha. — We  have  at  least  four  species  that  pertain  to 
this  genus.     The  Round-winged   Katydid,  A.   rotundi folia,   is  very 
common   throughout    the    Northern   States  and   Canada.      It    is  a 
small  species ;  the  length  of  the  body  is  20  mm.  (0.8  inch),  and  of 
the   tegmina   25   mm.  (i  'inch).     The   tegmina  are   wide    for   their 
length,  as  indicated  by  the  specific  name.     The  ovipositor  is  quite 
broad,   much   curved,   and   roughly   serrated.     The   Oblong-winged 
Katydid,  A.  oblongifolia,  occurs  in  the  same  region  as  the  preceding 
species  ;  it  is  larger,  has  longer  tegmina,  and  the   ovipositor  is  less 
serrate  and  less  curved.*     The  Tailed  Katydid,  A.  caiiddta,  occurs 
in  the  South ;  it  is  still  larger  than  the  preceding,  and  has  a  very 
long  ovipositor.     The  length  of  the  body^is  25  mm.  (i   inch),  of  the 
tegmina  37  mm.  (1.5  inches),  and  of  the  ovipositor  20  mm.  (0.8  inch). 
Uhler's  Katydid,  A.  Uhlerii,  is  our  smallest   species;  it  is  common 
in  Maryland  and  about  Washington. 

7,  Microcentrum. — The  Angular-winged  Katydid,  Microcentrum 
retinervis,  is  the  commonest  species  in  the  Western  and  Southern 
States.     It  is  especially  abundant  in  Florida,  where  it  often  injures 
the  foliage  of  young  orange-trees.     Its  eggs,  which  are  deposited  in 
one  or  two  rows   upon   twigs  or  the  margin  of  leaves,  frequently 
attract  attention  on  account  of  their  large  size  and  the  remarkable 
regularity  of  their  arrangement.     These  are  shown  natural  size  on 
Plate  III.     The  adult  female  and  several  nymphs  are  represented  at 
the  same  place.     Frequently  the  eggs  of  this  species  are  infested  by 
a  Chalcid   parasite,  Eupelmus    mirdbilis,   which  is  represented   en- 
larged on  the  same  plate  (2,  female ;   2#,  male).     There  is  a  closely 
allied   Katydid,  M.   affilidtum,   occurring   throughout    the   Eastern 
United  States,  which  is  larger,  and  which  differs  in  that  the  slightly 
hollowed   front  of  the   prothorax  has  a  very  small  central  tooth. 
This  is  a  rarer  species  than  the  preceding. 

*  Fig.  75  of  Harris's  "  Insects  Injurious  to  Vegetation"  is  of  A.  rotundi folia,  and  not 
of  this  species  as  indicated  in  the  text. 


PLATE    III. 


Il8  AN  INTRODUCTION    TO  ENTOMOLOGY. 

8.  Scudderia. — The    Narrow-winged    Katydid,    Scudderia   curvi- 
cauda,  is  the  common  species  of  this  genus.     It  is  quite  abundant  in 
many  parts  of   the   country.     The   tegmina  are   long  and   narrow, 
hence  the  common  name.     The  eggs  of  this  species  "  are  laid  singly 
in  the  edges  of  leaves,  between   the  upper  and  lower  cuticles,  and 
are  so  thin  that  they  are  not  noticeable  except  when  the  leaf  is  held 
between  one's  self  and   the  light.     They  swell  very  considerably, 
however,  in  the  spring,  before  hatching."     (Riley.) 

IV.    The  Shield-backed  Grasshoppers. 

9.  Thyreonotus. — These   are  wingless,  dull-colored   grasshoppers 
which  offer  a  striking  appearance,  owing  to  the  great  size  of  the  pro- 
notum.     This  segment  is  so  enlarged   as  to   extend   back   over  the 
other  two  thoracic  segments.     The  ovipositor  of  the  female  is  also 
greatly  developed,  and  is  nearly  straight.     We  have  in  the  eastern 
half  of  the  United  States  two  widely-spread  species.      T.  dorsdlis  has 


FIG.  106. —  Thyreonotus, 

the  pronotum  well  rounded  behind.  In  T.  pachymerus  (Fig.  106) 
it  is  nearly  square.  The  hind  legs  and  ovipositor  are  longer  in  T. 
dorsalis  than  in  the  other  species. 

In  the  region  west  of  the  Mississippi  River  are  found  wingless 
grasshoppers  which  are  known  as  "  Western  crickets."  These  belong 
to  the  genus  Anabrus.  This  genus  resembles  Thyreonotus  in  the 
shield-like  pronotum  and  the  large  size  of  the  ovipositor,  but  differs 
in  having  the  prosternum  unarmed,  while  in  the  former  genus  there 
are  two  spines  between  the  base  of  the  front  legs.  Three  species  of 
Anabrus  have  been  described.  "A.  color ddus  is  the  smallest,  and 
has  the  abdomen  distinctly  marked  by  transverse  bands;  A. purpu- 
rdscens,  dark  purplish  brown,  mottled  with  yellow ;  A.  simplex,  dark 
shining  brown.  This  species  varies  considerably  in  color,  being 
found  of  every  shade  from  light  brownish  yellow  to  almost  entirely 
black ;  specimens  are  sometimes  found  that  are  partly  yellow  and 
partly  black  or  dark  purple."  A.  simplex  is  sometimes  very  destruc- 
tive to  crops. 


ORTHOPTERA. 

Family  VII. — GRYLLIM;.* 


The  Crickets  constitute  the  last  of  the  three  families  embraced 
in  the  section  Saltatoria.  They  agree  with  the  members  of  the  pre- 
ceding family,  the  Locustidae,  in  the  possession  of  long,  slender, 
delicately-tapering  antennae,  and  differ  in  the  form  of  the  tegmina, 
the  number  of  segments  in  the  tarsi,  and  the  form  of  the  ovipositor. 
The  tegmina  in  the  Gryllidae  are  horizontal,  with  the  outer  portion 
bent  abruptly  downwards  ;  the  tarsi  are  three-jointed,  except  in  (Ecan- 
thus,  which  has  the  hind  tarsi  four-jointed,  and  the  ovipositor  is 
usually  long  and  spear-shaped. 

With  most  species  of  crickets  the  two  sexes  differ  greatly  in  ap- 
pearance. The  female  has  a  long  ovipositor,  and  the  venation  of 
the  tegmina  is  simple,  while  the  male  has  the  veins  upon  the  hori- 
zontal part  of  the  tegmina  so  modified  as  to  admit  of  their  being 
used  as  a  musical  organ. 

During  the  latter  part  of  the  summer  and  in  the  autumn,  the  air 
is  filled  with  the  cries  of  the  crickets.  With  care  it  is  easy  to  ob- 
serve these  little  fiddlers  calling  their  mates.  The  common  field- 
crickets  lurk  in  holes  in  the  ground  and  under  stones,  or,  emerging 
from  these  retreats,  run  through  the  grass  in  search  of  food.  At 
the  season  indicated  above,  the  male  crickets  spend  much  time  at 
or  near  the  entrance  of  their 
burrows,  making  their  pecu- 
liar calls.  So  intent  upon 
this  are  they,  that  by  moving 
quietly  one  can  approach 
sufficiently  near  to  watch 
them  carefully.  And  even 
when  they  are  disturbed  they 
retreat  into  their  holes  only 
for  a  short  time,  if  all  re- 
mains still.  At  night  they 
can  be  observed  by  means 
of  a  lantern,  as  light  does 
not  disturb  them.  In  order 
to  understand  the  manner 

of   making   these   calls,  it  is   necessary   to  study  the    structure  of 
the   tegmina.       In    the    male    crickets   these  organs  differ   greatly 


FIG.  107.— Tegmina  of  male  Gryllus. 


*  Gryllidffi,  Gryllus:  gryllus,  a  cricket. 


I2O  AN  INTRODUCTION    TO  ENTOMOLOGY. 

from  the  simple  form  seen  in  the  females.  In  Fig.  107,  a  represents 
the  tegmina  of  a  male  Gryllus.  It  will  be  seen  that  the  large  veins 
divide  the  wing  into  disk-like  membranous  spaces.  If  the  principal 
vein,  which  extends  diagonally  across  the  base  of  the  wing,  be  ex- 
amined with  a  microscope,  it  will  be  seen  to  be  furnished  with 
transverse  ridges  like  a  file  (Fig.  107,  b).  On  the  inner  margin  of  the 
wing,  a  short  distance  towards  the  base  from  the  end  of  the  principal 
vein,  there  is  a  hardened  portion  which  may  be  called  the  scraper. 
This  is  shown  enlarged  at  c  in  the  figure.  Each  tegmina  is  therefore 
provided  with  a  file  and  scraper.  When  the  cricket  wishes  to  make 
his  call,  he  elevates  his  tegmina  at  an  angle  of  about  forty-five  de- 
grees with  the  body;  then  holding  them  in  such  a  position  that  the 
scraper  of  one  rests  upon  the  file  of  the  other,  he  moves  the  tegmina 
back  and  forth  laterally,  so  that  the  file  and  scraper  rasp  upon  each 
other.  This  throws  the  tegmina  into  vibration,  and  produces  the  call. 
The  Gryllidae  is  a  comparatively  small  family,  but  the  American 
species  have  not  yet  been  monographed.  The  few  genera  which  I 
have  selected  as  illustrations,  and  which  are  our  most  common  ones, 
can  be  separated  by  the  following  table : 

A.  Fore  tibiae  broad,  fitted  for  digging.     (Fossorial  Crickets.) 
B.  Insect  small ;  antennae  ten- to  twelve-jointed.  i.  TRIDACTYLUS. 

BB.  Insect  large ;  antennae  many-jointed.  2.  GRYLLOTALPA. 

AA.  Fore  tibiae  slender. 

B.  Hind  femora  stoutish.     (True  Crickets.) 

C.  Last  segment  of  the  maxillary  palpi  of  the  same  length  a§  the  next 

to  the  last.  3.  GRYLLUS. 

CC.  Last  segment  of  the  maxillary  palpi  double  the  length  of  the  next  to 

the  last.  4.  NEMOBIUS. 

BB. Hind  femora  slender.     (Tree-crickets.)  5.  CECANTHUS. 

The  Fossorial  Crickets. — We  have  two  genera  representing  this 
group ;  they  are  commonly  known  as  Mole-crickets.  There  are 
species  belonging  to  the  next  group,  the  true  crickets,  which  burrow 
in  the  ground  ;  but  the  mole-crickets,  as  their  common  name  indi- 
cates, are  pre-eminently  burrowers.  The  form  of  the  body  is  that 
suited  to  this  mode  of  life.  The  front  tibise,  especially,  are  fitted  for 
digging.  They  are  greatly  broadened,  and  shaped  somewhat  like  a 
hand,  or  the  feet  of  a  mole.  Gryllotalpa  is  the  better  known  of 
these  two  genera,  this  is  doubtless  owing  to  the  large  size  of  the  spe- 
cies. The  Northern  Mole-cricket,  Gryllotalpa  bor edits,  inhabits  nearly 
the  whole  of  the  United  States  east  of  the  great  plains,  from  Lou- 
isiana to  Massachusetts.  It  is  not  a  common  insect,  but  occasion- 
ally it  is  found  in  great  numbers  in  a  limited  locality.  It  can  be 


ORTHOPTERA.  121 

easily  recognized  by  the  accompanying  figure,  which  represents  the 
insect  natural  size.  They  make  burrows  in  moist  places  from  six  to 
eight  inches  below  the  surface  of  the  ground,  and 
feed  upon  the  tender  roots  of  various  plants. 
In  Europe,  where  mole-crickets  are  more  abun- 
dant, they  are  frequently  serious  pests  in  culti- 
vated fields ;  and  in  the  West  Indies  there  is  a 
species  which  is  very  destructive  to  sugar-cane. 
The  species  of  Tridactylus  resemble  Gryllotalpa 
somewhat  in  form,  but  are  very  much  smaller; 
our  species  are  all  less  than  10  mm.  (0.4  inch)  in 
length.  They  also  resemble  the  large  mole- 
crickets  in  habits,  burrowing  in  similar  places. 
But  they  differ  in  having  their  hind  legs  formed 
for  leaping,  and  are  able  to  jump  as  well  as  the 
true  crickets.  At  Ithaca  we  find  Tridactylus 
very  local  in  its  distribution.  A  large  number 
of  specimens  have  been  taken  from  a  small  FlG-  IQ8-  — 

borealzs. 

spot  on   the  margin  of  one  of  our  streams,  but 

a  most  careful  search  has  failed  to  reveal  its  presence  elsewhere  in 

our  region. 

The  True  Crickets. — The  true  crickets  abound  everywhere,  in 
pastures,  meadows,  and  gardens ;  and  certain  species  enter  our 
dwellings.  They  are  chiefly  solitary,  nocturnal  insects ;  yet  many 
can  be  seen  in  the  fields  in  the  daytime.  They  usually  feed  upon 
plants,  but  are  sometimes  predaceous.  The  eggs  are  laid  in  the 
autumn,  usually  in  the  ground,  and  are  hatched  in  the  following 
summer.  The  greater  part  of  the  old  crickets  die  on  the  approach 
of  winter;  but  a  few  survive  the  cold  season.  The  greater  part 
of  the  species  of  our  true  crickets  are  included  in  the  two  genera 
Gryllus  and  Nemobiiis.  To  the  former  genus  belongs  our  larger 

species.  The  two  larger  of  our 
species  are  Gryllus  luctuosus  and 
Gryllus  abbrevidtus  (Fig.  io8#).  The 
species  of  the  genus  Nemobius  are 
much  smaller  than  Gryllus,  and  are 
characterized  by  the  greater  length 
FIG.  i&a.—GryiiHs  abbreviate.  of  the  last  segment  of  the  maxillary 

palpi.     The   most  common   species, 

and  one  that  is  very  abundant  in  our  fields  during  the  latter  part 
of  summer  and  autumn,  is  Nemobius  vittatus. 


122 


AN  INTRODUCTION  TO  ENTOMOLOGY. 


The  Tree-crickets. — Our  common  Tree-crickets  belong  to  the 
genus  CEcanthus.  The  most  abundant  species  is  the  Snowy  Tree- 
cricket,  CEcanthus  nlveus  (Fig.  109).  This  is  a  delicate  greenish- 
white  insect.  The  male  is  represented 
in  the  figure.  The  closely-folded  wings 
can  be  seen  through  the  transparent 
tegmina.  The  wings  vary  greatly  in 
length ;  sometimes  they  are  longer 
than  the  tegmina,  and  sometimes  not 
as  long.  In  the  females  the  tegmina 
are  wrapped  closely  about  the  body, 


FIG.  109. — CEcanthus  nzveus,  male. 


FIG.  no.  — Stem  of  blackberry  with  eggs  of  (Ecanthu 
niveus.  c,  egg  enlarged  ;  d,  ornamentation  of  egg 
(From  Riley.) 


making  the  insect  much  narrower  than  its  mate.  The  female 
lays  her  eggs  in  a  longitudinal  series  in  the  twigs  or  canes  of  various 
plants  (Fig.  no).  She  selects  the  raspberry  more  often  than  any 
other  plant ;  and  as  that  portion  of  the  cane  beyond  the  incisions 
made  for  the  eggs  usually  dies,  it  often  happens  that  these  crickets 
materially  injure  the  plants.  In  such  cases  the  dead  canes  should  be 
cut  out  and  burned  early  in  the  spring  before  the  eggs  hatch. 


CHAPTER    VII. 

Order  IV.— PHYSOPODA.* 

(Thrips.) 

The  members  of  this  order  have  four  wings  ;  these  are  similar  in 
form,  long,  narrow,  membranous,  not  folded,  with  but  few  or  no 
veins,  and  only  rarely  with  cross-veins  ;  they  are  fringed  with  long 
hairs  ;  and  are  laid  horizontally  along  the  back  when  at  rest.  The 
metamorphosis  is  incomplete.  The  mouth-parts  are  probably  used 
chiefly  for  sucking;  they  are  intermediate  in  form  between  those  of 
the  sucking  and  those  of  the  biting  insects  ;  the  mandibles  are  bristle- 
like  ;  the  maxilla  are  triangular,  flat,  and  furnished  with  palpi ;  and 
the  labial  palpi  are  also  present.  The  tarsi  are  two-jointed,  bladder- 
like  at  tip,  and  without  claws. 

These  are  insects  of  minute  size,  rarely  exceeding  2  mm.  or  3  mrn. 
in  length.  They  can,  however,  be  obtained  easily  from  various 
flowers,  especially  those  of  the  daisy  and  clover.  Ordinarily,  it  is 
only  necessary  to  pull  apart  one  of  these  flowers  to  find  several 
specimens  of  Thrips.  They  are  in  many  cases  very  active  insects, 
leaping  or  taking  flight  with  great  agility.  In  case  they  do  not  leap 
or  take  flight  when  alarmed,  they  are  apt  to 
run  about  and  at  the  same  time  turn  up  the 
end  of  the  abdomen  in  a  threatening  manner, 
as  if  to  sting.  In  this  respect  they  resemble 
the  Rove-beetles. 

The  body  is  long  (Fig.  ill).  The  head 
is  narrower  than  the  thorax,  without  any  dis- 
tinct neck ;  the  eyes  are  large,  with  conspic- 
uous ocelli ;  there  are  also  usually  three 
simple  eyes.  The  ventral  side  of  the  head  is  Fio  ^l_ 

prolonged  into  a  conical  beak,  which  extends  be- 
neath the  prosternum.  The  form  of  the  mouth-parts  can  only  be 
made  out  by  dissection  and  the  use  of  high  powers  of  the  micro- 
scope. Fig.  112  represents  the  mouth-parts  of  one  of  our  common 


*  Physopoda  :  physao  (<f>v craoj),  to  blow  up;  pous  (itovS),  a  foot. 


124 


AN  INTRODUCTION   TO  ENTOMOLOGY. 


FIG.  112. — Mouth-parts  of  Thrips.  (Drawn 
by  J.  M.  Stedman,  under  the  author's  di- 
rection.) 8.  labrum;  10,  mandible;  u,  max- 
illa; 12,  labium. 


the  wings  sug- 
Thysanoptcra,  by 
is  designated  in 


species.  The  mandibles  are  long,  bristle-like,  curved,  and  somewhat 
flattened  at  the  base  ;  the  maxillae  are  broad  at  the  base,  and  taper 
to  a  point ;  they  are  furnished  with  well-developed  palpi ;  the  labial 

palpi  are  distinct,  but  less  conspic- 
uous ;  the  labrum,  in  the  form  fig- 
ured, is  furnished  with  a  curious 
appendage  at  its  tip ;  and  the  la- 
bium is  deeply  emarginate.  The 
three  thoracic  segments  are  well 
developed.  The  wings  are  laid 
horizontally  on  the  back  when  not 
in  use  ;  they  are  very  narrow,  but 
are  fringed  with  long  hairs,  which, 
diverging  in  flight,  compensate  for 
the  smallness  of  the  membrane. 
This  fringing  of 
gested  .  the  name 
which  the  order 

many  entomological  works.  In  some 
species  the  wings  are  wanting.  The  legs  are  well  developed, 
but  are  furnished  with  very  peculiar  tarsi;  these  are  two-jointed, 
and  are  bladder-like  at  the  tip.  It  is  this  character  that  suggested 
the  name  Physopoda.  The  abdomen  is  more  or  less  spindle-form  ;  it 
is  terminated  in  some  genera  by  a  long,  slender  segment ;  in  others, 
the  females  are  furnished  with  a  four-valved  ovipositor,  which  lies 
in  a  groove  on  the  ventral  aspect  of  the  abdomen. 

"  The  larva  resembles  the  perfect  insect,  but  has  a  softer  body, 
with  the  mesothorax  and  metathorax  distinct ;  the  mouth  is  like 
that  of  the  adult;  the  antennae  and  legs  are  shorter;  there  are  no 
simple  eyes ;  and  the  compound  ones  are  replaced  by  conglomerate 
eyes.  The  pupa  resembles  the  perfect  insect,  but  the  articulations 
of  the  limbs  are  obscured  by  a  film,  and  the  wings  inclosed  in  short 
fixed  sheaths.  The  antennae  are  turned  back  on  the  head,  and  the 
insect,  though  it  moves  about,  is  much  more  sluggish  than  in  the 
other  states/'  (Haliday.) 

The  different  species  of  Thrips  vary  greatly  in  habits,  some  being 
injurious  to  vegetation,  while  others  are  carnivorous.  It  should  be 
borne  in  mind  that  the  insect  commonly  called  The  Thrips,  that  in- 
fests the  leaves  of  grape,  is  not  a  member  of  this  order,  but  one  of 
the  Leaf-hoppers  (family  Jassidae  of  the  order  Hemiptera).  The 


PHYSOPODA.  I25 

misapplication  of  the  name  Thrips  to  this  insect  is  often  the  cause 
of  confusion. 

In  taking  up  the  Physopoda,  it  seems  very  probable  that  we  re- 
turn again  to  near  the  foot  of  the  insect  series  as  represented  by 
living  forms.  This  is  indicated  by  the  Campodea-like  formvof  the 
body,  the  presence  of  rudimentary  abdominal  legs  in  a  European 
species,  and  the  Podura-like  habit  of  jumping  of  many  forms. 

These  insects  have  been  placed  in  various  positions.  But  the 
structure  of  the  mouth,  and  the  character  of  the  wings,  throw  them 
out  of  any  of  the  accepted  orders.  And  now  the  majority  of  ento- 
mologists agree  in  assigning  them  the  rank  of  a  distinct  order.  As 
to  the  position  of  this  order,  it  seems  to  me  that  it  is  the  lowest 
living  representative  of  one  of  the  lines  of  development  of  winged 
insects,  of  which  line  the  Hemiptera  is  the  culmination. 

The  Physopoda  has  not  been  thoroughly  studied.  The  most 
important  paper  on  the  insects  of  this  order  is  by  A.  H.  Haliday. 
This  was  published  in  the  Entomological  Magazine  for  1836.  It  is 
entitled  An  Epitome  of  the  British  Genera,  in  the  Order  Thysanop- 
tera,  with  Indications  of  a  few  of  the  Species.  Although  this  article 
was  published  more  than  a  half  century  ago,  and  was  intended  only 
to  include  the  British  genera,  it  is  the  most  complete  account  we 
have  of  the  order.  The  following  classification  is  compiled  from  it  : 

Sub-Order  I.— TUBULIFERA.* 

This  sub-order  is  characterized  by  the  absence  of  a  borer  in 
the  females,  and  by  having  the  last  abdominal  segment  in  both 
sexes  elongated,  narrow,  and  tubular.  The  maxillary  palpi  are  two- 
jointed,  with  the  first  segment  very  short ;  the  wings  are  without 
veins ;  the  two  pairs  are  of  the  same  structure  ;  they  are  naked,  ex- 
cept the  marginal  fringe  of  hairs  ;  and  when  at  rest,  they  are  crossed 
so  as  to  lie  upon  each  other  upon  the  abdomen. 

This  sub-order  includes  a  single  family,  the  Tubuliferidce.  And 
only  a  single  genus,  Phloeothrips,  representing  this  family,  was  de- 
scribed by  Haliday. 

Phlceot /trips. — Here  belong  the  more  common  of  the  black  thrips 
which  abound  in  the  flowers  of  clover  and  daisy ;  they  are  also 
found,  as  their  name  indicates,  under  the  bark  of  trees. 

*  Tubulifera:  tubulus,  a  small  tube;  fero,  to  bear. 


126  AN  INTRODUCTION    TO  ENTOMOLOGY. 

Sub-Order  II.— TEREBRANTIA  * 

This  sub-order  is  characterized  by  the  presence  in  the  female  of 
a  four-valved  borer.  The  maxillary  palpi  are  three-jointed  ;  the  two 
pairs  of  wings  differ  somewhat  in  structure ;  the  first  pair  is  some- 
what longer,  and  wider,  and  usually  also  thicker  ;  sometimes  they 
are  almost  horny ;  both  pairs  are  clothed  with  numerous  very  fine 
hairs ;  the  front  wings  have  two  parallel  veins,  the  hind  wings  a 
single  vein  or  none ;  the  veins  of  the  wings  usually  bear  conspicu- 
ous spines ;  the  wings,  when  not  in  use,  are  folded  parallel  to  each 
other  on  the  abdomen. 

The  members  of  this  sub-order  are  much  more  agile  than  those 
of  the  preceding.  They  run  rapidly,  and  spring,  by  bending  under 
the  tip  of  the  abdomen  and  suddenly  straightening  it  out. 

The  Terebrantia  includes  two  families ;  these  can  be  separated 
as  follows : 

A.  Females  with  borer  curved  downwards.  Fam.  II. — STENOPTERIDVE. 

A  A.  Females  with  borer  curved  upwards.  Fain.  III.— COLEOPTRATID^E. 

Family  II. — STENOPTERiD^.f 

In  the  Stenopteridae  the  wings  are  narrow  and  are  furnished 
with  one  or  two  longitudinal  veins ;  but  there  are  no  cross-veins. 
The  longitudinal  veins  are  usually  fringed  with  spines.  There  are 
two  or  three  small  indistinct  segments  at  the  end  of  the  antennae. 
An'd,  as  stated  above,  the  ovipositor  of  the  female  is  curved  down- 
wards. This  family  includes  the  greater  number  of  the  members  of 
the  order.  The  following  table  will  aid  in  determining  the  genera: 

A.  Body  above  netted  with  elevated  lines.  i.  HELIOTHRIPS. 
AA.  Body  smooth. 

B.  Abdomen  clothed  with  silky  hairs.  2.  SERICOTHRIPS. 
BB.  Body  glabrous. 

C.  Prothorax  produced  in  front  and  narrowed.  3.  CHIROTHRIPS. 
CC.  Prothorax  not  narrowed. 

D.  Last  segment  of  abdomen  armed  with  paired  spines  in  the  female ; 

male  wingless.  4.  LIMOTHRIPS. 
DD.  Last  segment  unarmed. 

E.  The  last  two  segments  of  the   antennae  shorter  than  the  sixth 

segment.  5.  THRIPS. 

EE.  The  last  two  segments  of  the  antennae  longer  than  the  sixth 

segment.  6.  BELOTHRIPS. 


*  Terebrantia:  terebro,  to  bore  through. 

f  StenoptSridae :  stenos  (orevoS),  narrow;  pteron  (xrepor),  a  wing. 


PHY  SO  POD  A.  127 

The  most  abundant  members  of  this  family  pertain  to  the  genus 
Limothrips.  There  is  a  light  yellow  species  which  swarms  in  the 
flowers  of  clover  and  daisies.  Another  common  species  I  have  desig- 
nated, in  my  "  Notes  on  Entomology,"  as  The  Grass-eating  Thrips, 
Limothrips  podphagus.  The  injury  caused  by  this  pest  often  attracts 
attention,  although  the  insect  itself  is  rarely  observed.  It  infests 
timothy  and  June-grass,  causing  the  head  to  turn  yellow  and  die 
before  maturing.  These  dead  heads  are  very  abundant  every  year. 
By  pulling  the  head  from  its  sheath,  the  stalk  will  be  found  to  be 
shrunken  in  the  tender  part  just  above  the  joint,  where  the  juice 
has  been  sucked  from  it  ;  and  in  this  place,  if  the  examination  be 
made  soon  after  the  turning  yellow  of  the  head,  the  insect  can  also 
be  found.  The  adult  female  is  light  yellow  in  color,  measures  from 
i  mm.  to  i^  mm.  (0.04  inch  to  0.05  inch)  in  length,  and  is  remark- 
able in  lacking  the  long  spines  on  the  veins  of  the  wings. 

Family  III.  —  COLEOPTRATIM;.* 

This  family  is  characterized  by  having  the  ovipositor  of  the 
female  curved  upwards.  The  front  wings  are  broader  than  in  the 
preceding  family,  and  are  furnished  with  both  longitudinal  and 
cross  veins.  The  following-named  genera  are  indicated  by  Haliday  : 

A.  Antennae  with  nine  distinct  segments.  i.  MELANTHRIPS. 

AA.  Antennae  apparently  five-jointed,  the  last  four  segments  being  minute 
and  compact. 

B.  Body   somewhat  flattened  ;    mesothorax  and  metathorax  broad  ;   front 

wings  without  fringe  on  costal  border,  and  with  four  cross  veins;  males 

with  lateral  abdominal  appendages.  2.  COLEOTHRIPS. 

BB.  Body  cylindrical  ;  mesothorax  and  metathorax  constricted,  wings  rudi- 

mentary. 3-  ^EOLOTHRIPS. 


*Coleoptratidae:  coleopteros  (tfoAeoTrrepoS),  sheath-winged. 


CHAPTER  VIII. 

Order  V.— HEMIPTERA.* 

(Bugs,  Plant-lice,  Bark-lice,  et  al.} 

The  members  of  this  order  have  four  wings  ;  in  one  sub-order  the 
first  pair  of  wings  are  of  the  same  thickness  throughout,  and  itsually 
slope  at  the  sides  of  the  body ;  in  another  sub-order  the  first  pair  of 
wings  are  thickened  at  the  base,  with  thinner  extremities  which  over- 
lap on  the  back.  The  mouth-parts  are  formed  for  sucking.  The 
metamorphosis  is  incomplete. 

The  Hemiptcra  comprises  the  insects  which  are  properly  called 
bugs.  This  term  is  commonly  applied  to  any  thing  that  creeps  or 
crawls  ;  but  the  entomologist  always  refers  to  a  member  of  this 
order  when  he  speaks  of  a  bug.  In  addition  to  the  general  term 
bug,  the  representatives  of  some  of  the  families  are  known  by  special 
names,  as  plant-lice,  bark-lice,  leaf-hoppers,  water-boatmen,  and 
others.  The  order  is  a  very  important  one  ;  it  includes  many  spe- 
cies injurious  to  vegetation,  which  often  occur  in  such  great  numbers 
as  to  destroy  the  plants  infested.  On  the  other  hand,  some  of  the 
species  are  ranked  among  beneficial  insects  on  account  of  their  car- 
nivorous habits ;  while  still  others,  as  the  cochineal  and  lac  insects, 
furnish  us  with  useful  products. 

The  name  Hemiptera  was  suggested  by  the  form  of  the  front 
wings  in  the  sub-order  Heteroptera  ;  here  the  basal  half  of  these 
organs  is  thickened  so  as  to  resemble  the  elytra  of  beetles,  only  the 
terminal  half  being  wing-like.  The  second  pair  of  wings  are  mem- 
branous, and  are  folded  beneath  the  first  pair.  On  this  account,  the 
latter  are  often  termed  wing-covers ;  they  are  also  termed  hemely- 
tra,  a  word  suggested  by  their  structure. 

The  wing-covers  of  the  Heteroptera  present  characters  much 
used  in  classification  ;  and  consequently  special  names  have  been 
applied  to  the  different  parts.  The  thickened  basal  portion  is 

*  Hemiptera:  hemi-  (rfni-},  half;  pteron  (Ttrepor),  a  wing. 


HEMIPTERA. 


I29 


composed  of  two  pieces  joined  together  at  their  sides  ;  one  of  these 
is  narrow,  and  is  the  part  next  to  the  scutellum  when  the  wings  are 
closed  (Fig.  113,  Cl)\  this  is  distinguished  as  the  cldvus: 
the  other  broader  part  is  the  corium  (Fig.  113,  Co). 
The  terminal  portion  of  the  wing-cover  is  designated 
as  the  membrane  (Fig.  113,  M).  In  certain  families,  a  FIG.  n3.- 
triangular  portion  of  the  terminal  part  of  the  corium  is  winf<^e°f 
separated  as  a  distinct  piece  (Fig.  113,  Cu) ;  this  is  the 
ciineus.  In  certain  other  cases,  a  narrow  piece  on  the  costal  mar- 
gin of  the  corium  is  separated  (Fig.  113,  E)\  this  is  the  embolium. 
Both  pairs  of  wings  in  the  Homoptera  and  Heteroptera  are  furnished 
with  veins ;  but  it  is  not  necessary  for  the  purposes  of  this  work  to 
discuss  here  the  nomenclature  of  these  veins. 

The  mouth-parts  are  formed  for  piercing  and  sucking.     Without 
dissection,  they  usually  appear  as  a  slender  jointed  beak,  arising  at 
the  base  of  a  shorter  pointed  labrum.     This  beak  consists  of  four 
bristles  inclosed    in  a   fleshy,  jointed  sheath  (Fig.   1 14). 
Two  of  the  bristles  represent   the   mandibles,  and  two 
the  maxillae.     The  sheath  is  supposed  to  consist  of  the 
labium  and  the  grown-together  labial  palpi.  This  sheath 
is  usually  four-jointed,  and  is  never  composed  of  more 
than    that  number  of   segments.     The  maxillary  palpi 
are  wanting. 

Most  of  the  Heteroptera  protect  themselves  by  the 
emission  of  a  disagreeable  odor.     This  is  caused  by  a 
fluid  which  is  excreted    through  two  openings,  one   on 
each  side  of  the  ventral  aspect  of  the  thorax,  behind  or 
near   the    middle   coxa.      These    openings   are    termed 
FMouth-ptrw    the  ost  coles.     Each  of  these  is  usually  in  some  kind  of 
?eHM£hr()Af~    an  open  channel  styled  the   ostcolar   canal,    and  this  is 
surrounded  by  a  more    or  less    rugged   and   granulated 
space,   the  evaporating  surface.     The  legs  of  the  Hemiptera  vary 
greatly  in  form,  but  the  tarsi  are  never  more  than  three-jointed. 

The  lateral  margin  of  the  abdominal  segments  is  much  devel- 
oped in  several  families,  and  forms  a  flat,  reflexed  or  vertical  border 
to  the  abdomen,  which  is  called  the  connexlvum. 

In  their  transformations  the  Hemiptera  pass  through  an  incom- 
plete metamorphosis.  The  rudimentary  wings  of  the  nymphs  lie 
in  the  normal  position,  with  the  lower  side  of  the  wing  next  to  the 
body,  and  not  inverted  as  with  the  Jumping  Orthoptera.  The 


130  AN  INTRODUCTION   TO  ENTOMOLOGY. 

males  of  the  Coccidae  present  a  remarkable  exception  in  the  nature 
of  their  transformations,  the  metamorphosis  being  a  complete  one. 

This  order  includes  three  well-marked  groups  ;  these  are  ranked 
as  sub-orders,  and  are  distinguished  as  follows  : 

TABLE   OF   SUB-ORDERS   OF  HEMIPTERA. 

A.  Wingless  Hemiptera,  parasitic  upon  Man  and  other  Mammals,  with  a  fleshy 
unjointed  rostrum.*  I.  PARASITA. 

AA.   Hemiptera  with  or  without  wings,  but  with  a  jointed  rostrum. 

B.  Wings  of  the  same  thickness  throughout,  and  usually  sloping  at  the  sides 
of  the  body;  rostrum  arising  from  the  hinder  part  of  the  lower  side  of 
the  head  ;  head  without  neck,  and  so  closely  applied  to  the  prothorax 
that  the  first  pair  of  coxae  articulate  with  the  cheeks.  II.  HOMOPTERA. 
BB.  First  pair  of  wings  thickened  at  the  base,  and  with  thinner  extremities, 
which  overlap  on  the  back  ;  rostrum  arising  from  the  front  part  of  the 
head  ;  head  (except  in  Corisidce  and  Notonectidce)  with  a  more  or  less  dis- 
tinct neck,  so  that  the  cheeks  and  the  first  pair  of  coxae  do  not  touch 
each  other.  III.  HETEROPTERA. 

Sub-Order  I.—  PARASITICA. 

The  Parasltica  includes  certain  parasites  of  Man  and  other  Mam- 
mals, commonly  known  as  lice.  All  the  species  which  have  been 
found  in  the  United  States  belong  to  a  single  family,  the  Pedicu- 
lidce.  We  will  not,  therefore,  enter  into  a  discussion  of  the  charac- 
ters of  the  sub-order,  but  pass  directly  to  a  study  of  this  family. 


Family  I.— 

(Lice.} 

The  lice  are  very  small,  wingless  insects,  which  live  on  the  skin  of 
Mammalia,  and  suck  their  blood.  The  mouth  is  furnished  with  a 
fleshy,  unjointed  proboscis,  which  can  be  withdrawn  into  the  head, 
or  extended  to  a  considerable  length.  Within  this  proboscis  are 
two  protrusible  knife-like  stylets  ;  and  at  its  base,  when  extended, 
there  is  a  wreath  of  re-curved  hooks.  These  hooks  serve  to  anchor 
firmly  the  proboscis  when  inserted  in  the  skin  of  the  infested  ani- 
mal. The  eyes  are  two  in  number,  small  and  simple.  The  antennae 
have  five  segments.  The  legs  are  joined  to  the  outer  margin  of  the 

*  This  is  true  of  all  forms  that  have  been  found  in  the  United  States.  But  in  the 
genus  Polyctenus  the  rostrum  is  three-jointed.  Two  species  of  this  genus  are  known  ; 
these  infest  bats  ;  one  in  the  West  Indies,  the  other  in  China. 

\  Pediculus,  a  louse. 


HEMIPTERA.  ^ 

thorax.  They  are  fitted  for  climbing,  being  furnished  with  a  pow- 
erful curved  claw  at  the  tip  of  the  tarsus,  which  is  opposed  by  a 
toothed  projection  of  the  tibia.  This  arrange- 
ment  is  admirably  adapted  for  clinging  to  hairs. 
The  young  do  not  undergo  a  metamorphosis. 
Only  a  few  species  pertaining  to  this  family  are 
known.  The  bird-lice,  which  differ  from  the 
true  lice  in  having  biting  mouth-parts,  consti- 
tute the  family  Mallophagidce,  of  the  order 
Pseudoneuroptera,  and  should  not  be  con- 
founded with  the  insects  we  are  now  de- 
scribing. 

Three  species  of  lice  infest  man ;  these  are 
as  follows : 

The    head-louse,    Pediculus    cdpitis.  —  This         FlG-  "?•— 

asini.     (From  Law.) 

is    the   most    common   species   infesting   man. 

It  lives  in  the  hair  of  the  head,  and  is  found  upon  all 
races  of  men.  It  is  most  common  upon  the  heads  of  neglected 
children.  Its  general  color  is  pale  yellowish,  with  the  outer  edges 
of  the  thorax  and  abdomen  dark  brown  or  gray,  and  the  tarsal 
claws  pale  brown.  The  eggs  are  oval,  and  are  usually  glued  by  the 
pointed  end  to  the  hair  of  the  host.  These  "  nits"  are  said  to  hatch 
under  favorable  conditions  in  about  a  week  from  the  time  they  are 
laid.  Under  ordinary  circumstances,  cleanliness  and  the  use  of  a 
fine-toothed  comb  are  all  that  is  necessary  to  insure  freedom  from 
this  disgusting  pest. 

The  Body-louse,  Pediculus  vestimenti. — This  is  somewhat  larger 
than  the  preceding  species.  Like  the  head-louse,  it  infests  all  races 
of  men.  It  is  an  interesting  fact,  however,  that  peculiar  varieties 
have  been  developed  upon  the  different  races.  The  variety  which 
infests  the  Whites  in  this  country  is  yellowish,  tinged  with  gray ; 
"  that  of  the  West  African  and  Australian  is  nearly  black ;  of  the 
Hindoo,  dark  and  smoky;  of  the  Africander  and  Hottentot,  orange; 
that  of  the  Chinese  and  Japanese,  yellowish  brown  ;  of  the  Indians 
of  the  Andes,  dark  brown ;  of  the  Digger  Indians  of  California, 
dusky  olive  ;  and  that  of  the  more  North  American  Indians,  near  the 
Esquimaux,  paler,  approaching  to  the  light  color  of  the  parasites  of  the 
European."  *  This  insect  lives  upon  the  skin  of  most  parts  of  the 
body ;  but  especially  selects  the  chest  and  back.  It  is  often  trouble- 

*  Andrew  Murray,  Economic  Entomology,  p.  392. 


132 


AN  INTRODUCTION    TO  ENTOMOLOGY. 


some  on  ships,  in  military  camps,  in  prisons,  and  in  the  apartments 
of  uncleanly  people  who  neglect  to  change  their  clothes.  The  fe- 
male attaches  her  eggs  to  fibres  in  the  seams  of  undergarments, 
from  which  the  larvae  hatch  in  about  a  week.  This  species  is  ex- 
ceedingly prolific.  The  method  of  destroying  these  vermin  com- 
monly employed  in  hospitals  and  poorhouses  is  to  rub  mercurial 
ointment  in  the  seams  of  undergarments. 

The  Crab-louse,  Pkthirius  pubis. — The  common  name  of  this  spe- 
cies is  suggested  by  the  form  of  the  body,  which  is  nearly  as  broad 
as  long.  When  highly  magnified,  the  resemblance  of  this  insect  to 
a  crab  is  quite  striking ;  but  to  the  unaided  eye  it  appears  more  like 
a  large  scale  of  dandruff.  These  offensive  vermin  affect  the  pubic 
region  and  armpits  of  man,  stretching  themselves  out  flat,  holding 
tight  to  the  cuticle,  and  inflicting  most  irritating  punctures.  They 
can  be  destroyed  by  mercurial  ointment. 

The  true  lice  of  cattle,  of  the  horse,  ass,  swine,  squirrel,  etc.,  are 
very  closely  allied  to  the  head-louse  and  body-louse  of  man.  They 
have  been  placed,  however,  by  systematists  in  a  distinct  genus, 
Hcematoplnus.  The  names  of  the  more  important  species  are  as  fol- 


FIG.    116.— H.  eurysternus.     FIG.  117. — H.  vituli. 
(From  Law.)  (From  Law.) 


FIG.  118  —  H.  SMJ'S. 
(From  Law.) 


FIG.  ng.—ff.  piliferus. 
(From  Law.) 


lows:  louse  of  cow,  H.  eurysternvs  (Fig.  116);  a  second  species 
found  on  cattle,  especially  calves,  is  H.  vituli  (Fig.  117);  louse  of 
horse  and  ass,  H.dsini  (Fig.  115);  louse  of  swine,  H.  suis  (Fig  1 1 8) ; 
louse  of  the  dog,  H.  piliferus  (Fig.  119);  louse  of  rabbit,  H.  ventri- 
cosus  ;  louse  of  monkeys,  H.  quadrumanus. 


HEMIPTERA.  133 

The  reader  should  bear  in  mind  that  certain  of  the  bird-lice,  Mal- 
lophagidce,  infest  cattle,  the  horse,  ass,  sheep,  dog,  and  cat.  These 
pests  have  been  discussed  in  an  earlier  chapter.  The  true  lice  of 
the  genus  H&matopinus  can  be  recognized  by  the  figures  on  the 
two  preceding  pages. 

For  the  destruction  of  these  pests  upon  cattle,  poisonous  sub- 
stances must  not  be  used,  as  injury  would  result  from  the  animals' 
licking  themselves.  They  may  be  safely  treated  by  washing  with  a 
strong  infusion  of  tobacco  leaves,  or  by  rubbing  with  an  ointment 
made  of  one  part  sulphur  and  four  parts  lard,  or  by  sprinkling  with 
Scotch  snuff  or  powdered  wood-ashes.  The  insecticide  should  be 
applied  thoroughly,  leaving  no  spots  untouched  where  the  lice  can 
gather  and  remain,  and  from  which  they  can  spread  over  the  body 
again.  The  application  should  be  repeated  several  times  at  inter- 
vals of  three  or  four  days,  in  order  to  destroy  the  young  which  may 
hatch  after  the  first  application.  It  is  also  necessary,  in  order  to 
make  sure  of  eradicating  the  pests,  to  dress  with  similar  agents,  or 
with  strong  lye,  or  kerosene,  all  places  where  the  cattle  have  been  in 
the  habit  of  rubbing,  and  the  cracks  in  the  stables  where  they  have 
stood ;  or  to  whitewash  the  stables  and  rubbing-places. 

Sub-Order  II. -HOMOPTERA.* 

The  Homoptera  is  that  division  of  the  Hemiptera  in  which  the 
wings  are  of  the  same  thickness  throughout,  and,  when  at  rest,  usu- 
ally slope  roof-like  at  the  sides  of  the  body.  This  sub-order  is  also 
characterized  by  the  absence  of  a  neck,  and  the  position  of  the 
mouth-parts  at  the  hinder  part  of  the  lower  side  of  the  head.  So 
closely  is  the  head  applied  to  the  thorax  that  usually  the  front  coxae 
articulate  with  the  cheeks,  and  in  many  forms  the  mouth-parts  ap- 
pear to  arise  from  between  the  front  legs. 

Although  the  Homoptera  is  a  well-marked  group,  so  well  defined 
that  by  some  it  is  considered  a  distinct  order,  the  families  of  which 
it  is  composed  show  great  variations  in  structure,  and  modes  of  de- 
velopment of  the  species.  Some  of  the'  most  interesting  biological 
problems  presented  by  Entomology  have  arisen  in  the  study  of  this 
sub-order. 

TABLE   OF   FAMILIES  OF   HOMOPTERA. 

A.  Beak  apparently  arising  from  the  sternum,  or  absent ;  tarsi  one-  or  two- 
jointed  :  antennae  usually  prominent  and  filiform,  sometimes  wanting. 

*  Homoptera  :  homos  (ono$),  same;  pteron  (Trre/jci;'),  a  wing. 


134  AN  INTRODUCTION    TO  ENTOMOLOGY. 

B.  Tarsi  one-jointed  ;  adult  male  without  any  beak  and  with  only  two  wings  : 
female  wingless,  with  body  either  scale-like  or  gall-like  in  form,  or  grub- 
like,  and  clothed  with  wax.  The  waxy  covering  may  be  in  the  form  of 
powder,  of  large  tufts  or  plates,  of  a  continuous  layer,  or  of  a  thin  scale 
beneath  which  the  insect  lives.  2.  COCCID.E. 

BB.  Tarsi  usually  two-jointed;  wings,  when  present,  four  in  number. 

C.   Wings  opaque,  whitish  ;  wings  and  body  covered  with  a  whitish  pow- 
der. 3.  ALEYRODID^. 

CC.  Wings  transparent. 

D.   Legs  long  and  slender,  not  fitted  for   leaping  ;    antennae  three-  to 
seven-jointed.  4.  APHIDID^E. 

DD.   Hind  legs  fitted  for  leaping;  antennae  nine-  or  ten-jointed. 

5.    PSYLLID^:. 

AA.  Beak  evidently  arising  from  the  mentum  ;  tarsi  three-jointed  ;  antennae 
minute,  setiform. 

B.   With  three   ocelli,  and  the  males  with   musical  organs.     Usually  large 
insects,  with  all  the  wings  entirely  membranous.  7.  CICADID^E. 

BB.  Ocelli  only  two  in  number,  or  wanting  ;  males  without  musical  organs. 
C.  Antennas  inserted  on  the  side  of  the  cheeks  beneath  the  eyes. 

8.  .FULGORID^E. 

CC.  Antennae  inserted  in  front  of  and  between  the  eyes. 

D.  Prothorax  prolonged  into  a  horn  or  point  above  the  abdomen. 

6.  MEMBRACID^E. 
DD.  Prothorax  not  prolonged  above  the  abdomen. 

E.   Hind  tibiae  armed  with  one  or  two  stout  teeth,  and  the  tip  crowned 

with  short,  stout  spines.  9.  CERCOPID^. 

EE.   Hind  tibiae  having  a  double  row  of  spines  below.       10. 


Family  II.—  COCCID.E.* 
(Scale-insects  or  Bark-lice,  Mealy-bugs,  et  at.) 

The  family  Coccidce  includes  the  Scale-insects  or  Bark-lice, 
Mealy-bugs,  and  certain  other  insects  for  which  there  are  no  popu- 
lar names.  In  many  respects  this  is  a  very  anomalous  group,  the 
species  differing  greatly  in  appearance,  habits,  and  metamorphoses 
from  those  of  the  most  closely  allied  families.  Not  only  do  the 
members  of  this  family  appear  very  unlike  other  insects,  but  there 
is  a  wonderful  variety  of  forms  within  the  family  ;  and  even  the 
two  sexes  of  the  same  species  differ  as  much  in  the  adult  state  as 
members  of  distinct  orders. 

The  males  of  Coccidae,  unlike  all  other  Hemiptera,  undergo  a 
complete  metamorphosis.  The  adult  males  have  only  a  single  pair 

*C6ccidae,  Cficcus  :  coccum,  "the  berry  that  grows  upon  the  scarlet  oak."    This  sup- 
posed berry  was  a  bark-louse. 


HEMIPTERA, 


135 


of  wings,  the  hind  wings  being  represented  by  a  pair  of  club-like 
halteres.  Each  of  these  is  furnished  with  a  bristle,  which  in  all  of 
the  species  I  have  studied  is  hooked,  and  fits  in  a  pocket  on  the 
wing  of  the  same  side  (Fig.  120,  \a\  The  male  in  the  adult  state 
has  no  organs  for  procuring  food,  as  the  mouth-parts  disappear 


FIG.  120 — A sp idiotu s  nerii.     i,  scales  on  leaves  of  acacia,  natural  size;    i<»,  adult  male,  enlarged  ; 
scale  of  male,  enlarged  ;  ic,  scale  of  female,  enlarged.     (From  the  Author's  Report  for  1880.) 


during  the  metamorphosis  of  the  insect,  and  a  second  pair  of  eyes 
appear  in  their  place.  The  adult  female  is  always  wingless  ;  and  the 
body  is  either  scale-like  or  gall-like  in  form,  or  grub-like  and  clothed 
with  wax.  The  waxy  covering  may  be  in  the  form  of  powder,  of 
large  tufts  or  plates,  of  a  continuous  layer,  or  of  a  thin  scale,  be- 
neath which  the  insect  lives. 

Among  the  Coccidae  are  found  many  of  the  most  serious  pests  of 
horticulturists.  Scarcely  any  kind  of  fruit  is  free  from  their  attacks ; 
and  certain  species  of  scale-insects  and  mealy-bugs  are  constant  pests 
in  conservatories.  The  ease  with  which  these  insects  or  their  eggs 
can  be  transported  long  distances  while  yet  alive,  on  fruit  or  living 
plants,  has  caused  many  species  that  infest  cultivated  plants  to  be- 
come world-wide  in  distribution. 


136  AN  INTRODUCTION   TO  ENTOMOLOGY. 

During  recent  years,  much  attention  has  been  paid  to  devising 
methods  of  destroying  these  pests.  The  insecticides  which  are  now 
most  widely  used  are  alkaline  washes  and  kerosene  emulsion.  (See 
Chapter  XIV.) 

A  number  of  useful  insects  belong  to  this  family.  Several  species 
furnish  dye-stuffs.  The  best  known  of  these  is  Coccus  cacti,  the 
dried  bodies  of  which  are  known  as  Cochineal.  The  stick  lac  of 
commerce,  from  which  shell-lac  or  shellac  is  prepared,  is  a  resinous 
substance  excreted  by  one  of  the  Coccinae,  Carteria  lacca,  which 
lives  on  the  young  branches  of  several  tropical  trees.  And  the 
bodies  of  this  insect,  which  are  obtained  from  the  stick  lac,  furnish 
the  coloring  agent  known  as  lac  dye.  China  wax  is  another  sub- 
stance for  which  we  are  indebted  to  this  family.  It  is  the  excretion 
of  an  insect  known  as  Pe-la,  Ericerus  pe-la.  In  fact,  many  species  of 
this  family  excrete  wax  in  considerable  quantities.  I  have  found 
three  species  in  this  country  which,  if  they  can  be  easily  cultivated, 
produce  wax  in  sufficient  quantities  to  be  of  economic  importance. 

The  family  comprises  four  sub-families.  One  of  these  includes 
species  that  live  in  galls,  and  is  confined  to  Australia.  The  three 
sub-families  which  are  represented  in  our  fauna  can  be  separated  by 
the  following  table  :  * 


A.   Body  either  naked  or  clothed  with  a  secretion  ;  the  clothing,  however,  not 
in  the  form  of  a  scale  composed  in  part  of  moulted  skins. 

B.  Body  of  female  usually  remaining  distinctly  segmented, 
and  retaining  the  power  of  motion  till  maturity;  some- 
times, however,  it  becomes  more  or  less  globular  and  fixed, 
but  in  all  cases  the  labium  is  composed  of  several  seg- 
ments, and  there  are  no  anal  plates.  (Fig.  121,  ap^)  The 
abdomen  usually  ends  in  a  pair  of  lobes,  each  furnished 
with  one  or  more  bristles  (Plate  IV.  Fig.  le). 

i.  COGGING. 

BB.     Body  of  female  changing  much  in  form  during  develop- 
ment, becoming  scale-like  or  more  or  less  globular,  with 
the   segmentation   absent  or  indistinctly  indicated.      The 
FIG.    m.—Ltca-          individuals  usually  become  fixed  to  the  plant  upon  which 
"A  anal  pUtesrRed'          they  live ;  sometimes  they  are  enclosed  in   a   covering  of 
wax.     In  all  cases  the  labium  is  composed  of  a  single  seg- 
ment ;  the  caudal  opening  of  the  alimentary  canal  in  the  adult  female  is  covered 
by  a  pair  of  subtriangular  plates  (Fig.  121,  ap),  2  LECANINJE. 

^  *  The   characters    given  here  for  distinguishing  the    Lecanince    and    Coccinae   are 
merely  provisional,  as  these  groups  are  not  yet  well  known. 


PLATE   IV. 


138 


AN  INTRODUCTION    TO   ENTOMOLOGY. 


AA.  Body  of  insect  covered  by  a  scale  composed  in  part  of  moulted  skins  and 
partly  of  a  secretion  of  the  insect.  3.  DIASPHSUE. 

Sub-Family  I.— COCCIN^E. 

The  sub-family  Cocclnce  includes  those  Coccids  of  which  the 
females  undergo  the  least  change  in  form  during  their  development. 
The  majority  of  them  retain  a  form  not  much  different  from  that  of 
the  young  larvae  ;  but  in  some  genera  the  body  becomes  a  globular 
mass,  with  little  or  no  indication  of  segmentation.  The  most  im- 
portant characters,  as  the  family  is  now  understood,  are  the  multi- 
articulate  labium,  and  the  absence  of  anal  plates.  Plate  IV.  i<^rep~ 
resents  the  typical  form  of  the  female  adult  in  this  sub-family;  \e 
represents  the  caudal  end  of  the  body  of  the  same.  The  most  com- 
mon exception  to  this  form  is  that  of  the  genus  Kermes  described 
below.  In  most  genera  of  this  sub-family  the  body  of  the  female 
becomes  enclosed  in  a  cottony  or  felt-like  sac.  In  some,  as  the 
mealy-bugs,  this  takes  place  just  before  they  begin  to  oviposit ; 
while  in  other  genera  the  greater  part  of  the  life  of  tlie  insect  is 
passed  within  the  sac.  In  this  and  the  next  sub-family  the  caudal 
style  of  the  male  is  short ;  and  the  last  abdominal  segment  bears  a 
pair  of  long  waxy  filaments.  Each  filament  is  supported  by  one  or 
more  hairs,  at  the  base  of  which  are  the  spinnerets  from  which  the 
wax  is  excreted  (Plate  IV.  \a  and  \b]. 

Mealy-bugs,  Dactylopius. — The  mealy-bugs  are  the  best  known 

members  of  this  sub-family,  as  they  are 
the  most  common  and  most  noxious  of 
green-house  pests.  Fig.  122  represents 
D.  longifilis,  a  common  species  in  green- 
houses. D.  destructor  (Fig.  123)  is  an- 


FIG.  122. — Dactylopius  longifilis, 
female,  enlarged.  (From  the 
Author's  Report  for  1880.) 


FIG.  123. — Dactylopius  destructor, 
female,  enlarged.  (From  the 
Author's  Report  for  1880.) 


other  common  species,  which  differs  in  lacking  the  long  filaments 


HEMIPTERA.  139 

of  the  preceding  species.  This  occurs  in  green-houses  in  the  North, 
and  is  also  very  destructive  to  orange-trees  in  Florida. 

Cochineal,  Coccus  cacti. — This  is  a  native  of  Mexico,  but  is  now 
cultivated  in  India,  Spain,  and  other  countries.  It  feeds  upon  vari- 
ous species  of  the  Cactaceae,  more  especially  Opuntia  coccinilifcra. 
I  have  received  living  specimens  which  were  collected  upon  a  wild 
cactus  in  Florida.  The  dye-stuff  consists  of  the  female  insects, 
which,  when  mature,  are  brushed  off  the  plants,  killed,  and  dried. 
The  entire  insect  is  used.  From  cochineal,  lake  and  carmine  are 
also  prepared.  Cochineal  is  now  being  superseded  by  aniline  dyes, 
which  are  made  from  coal-tar. 

Orthczia.—^^z  members  of  this  genus  occur  not  uncommonly 
on  various  weeds.  They  are  remarkable  for  the  calcareous  secretion 
with  which  the  body  is  clothed.  This  is  in  the  form  of  long  plates. 
Fig.  124  represents  a  nymph  ;  in  the  adult  female,  the  excretion  be- 
comes more  elongated  posteriorly,  and  forms  a  sac  containing  the 
eggs  mixed  with  a  fine  down.  Later,  when  the  young  are  born, 
they  remain  in  the  sac  till  they  have  themselves  secreted  a  sufficient 
amount  of  the  lamellar  matter  to  cover  them. 


FIG.  ™,.-Orthezia,  enlarged.     (From  the  FIG.  ^.-Icerya  Purc 

Author's  Report  for  1880.)  and  young,  on  orange 

Report  for  1880.) 

-  leery  a  purchasi.— This  beautiful  insect  (Fig.  125)  is  one  of  the 
most  dangerous  pests  infesting  fruit-trees  in  California.  The  body 
of  the  adult  female  is  scale-like,  dark  orange-red,  and  has  the  dorsal 
surface  more  or  less  covered  with  a  white  or  yellowish-white  powder. 
The  insect  secretes  a  large  egg-sac,  which  causes  it  to  resemble  Pul- 


140 


AN  INTRODUCTION    TO  ENTOMOLOGY. 


vinaria,  of  the  next  sub-family.  The  egg-sac  of  Icerya,  however,  is 
beautifully  ribbed,  while  that  of  Pulvinaria  is  not  of  very  definite 
form.  Icerya  is  an  introduced  insect  from  Australia. 

Rhizococcus. — Two  species  of  Rhizococcus  are  figured  on  Plate  IV. 
Fig.  i  represents  R.  araucdrice,  a  species  infesting  Norfolk  Island 
pine  (Araucaria  excelsior]  in  southern  California ;  and  Fig.  2  is  of 
R.  quercus  upon  oak  from  Florida.  This  genus  is  a  good  illustration 


FIG,  126. — Kermes  sp.,  on  Quercus  agrifolia.    Adult  females  on  stem  ;  immature  males  on  leaves. 
(From  the  Author's  Report  for  1880.) 

of  the  forms  that  spend  a  greater  part  of  their  lives  within  sacs.  A 
more  common  illustration  of  this  occurs  in  the  genus  Eriococcus,  of 
which  we  have  a  species,  E.  azdlece,  common  upon  azaleas  in  con- 
servatories. 

Kermes. — The  most  abnormal  members  of  this  sub-family  consti- 
tute the  genus  Kermes.     Species   of  this  genus  are  common   upon 


HEMIPTERA.  14! 

oaks  wherever  they  grow.  These  insects  are  remarkable  for  the 
wonderful  gall-like  form  of  the  adult  females.  So  striking  is  this 
resemblance,  that  they  have  been  mistaken  for  galls  by  many  ento- 
mologists. Fig.  126  represents  a  species  of  this  genus  upon  Quercus 
agrifolia.  The  gall-like  swellings  on  the  stem  are  the  adult  females; 
the  smaller  scales  on  the  leaves  are  the  immature  males. 

Sub-Family  II. — LECANIN^E.* 

In  the  present  state  of  our  knowledge  of  this  sub-family  there  is 
nothing  to  add  to  the  characterization  of  it  given  in  the  table  on  page 
136.  The  most  available  character  for  recognizing  these  insects  is 
the  presence  of  the  subtriangular  anal  plates  (Fig.  121).  Usually, 
the  body  is  elliptical  or  circular  in  outline,  with  a  deep  incision  at 
the  caudal  end,  .leading  to  the  anal  opening  (Fig.  121).  Although 
as  a  rule  these  insects  remain  fixed  to  one  spot  after  the  wandering 
larval  stage,  I  have  seen  the  adults  of  certain  species  move  from  one 
place  to  another.  It  is  a  curious  fact  that  in  certain  species,  among 
them  the  most  common  ones,  as  L.  hesperidum,  the  males  are  un- 
known. It  seems  probable  that  they  rarely,  if  ever,  occur.  Only 
three  genera  have  been  found  in  the  United  States.  These  are  dis- 
tinguished as  follows : 

A.  Body  naked  or  nearly  so. 

B.  Female  secreting  a  mass  of  cottony  material  in  which  the  eggs  are  laid. 

Fig.    127.  2.    PULVINARIA. 

B.  Female  laying  her  eggs  beneath  her  body,  not  excreting  a  mass  of  cot- 
tony material.  i.  LECANIUM. 
AA.   Body  covered  with  a  layer  of  wax.                                     3.  CEROPLASTES. 

Lecdnium. — The  species  of  the  genus  Lecanium  abound  every- 
where ;  they  occur  on  all  kinds  of  plants  both  in  conservatories  and 
in  the  open  air.  Some  of  them  are  known  to  gardeners  as  "  Soft- 
scales."  The  genus  is  one  that  is  easily  recognized,  but  no  one  has 
yet  found  satisfactory  characters  for  separating  the  closely  allied 
species.  I  have  figured  three  of  the  more  common  forms.  Plate 
V.  2  is  of  Lecdnium  hesperidum.  This  is  a  representative  of  a  group 
that  includes  our  most  common  species.  They  are  an  elongated 
oval  in  outline,  nearly  flat,  and  smooth  and  shining. 

Lecdnium  hemispharicum  (Plate  V.  3)  is  a  much  more  convex 
species,  as  its  name  indicates.  It  is  common  in  conservatories. 

*LecanInse,  Lecanium  :  lecane  (^eKarrf),  a  dish 
IO 


PLATE   V. 


*»  I  V  xL 


HEMIPTERA. 


143 


Lecdnium  olea  also  occurs  in  conservatories,  but  it  is  very  common  in 
the  open  air  in  California.     Here  it  is  a  serious  pest  of  the  orange, 


FIG.  ivj.—Pulvinaria.  innumerabilis.     Female  on  grape,  natural  size.    (From  the  Author's  Report 

olive,  and  other  trees.  It  is  very  convex  and  marked  with  promi- 
nent ridges  (Plate  V.  i).  Especially  prominent  are  two  transverse 
ridges  and  a  longitudinal  one  which  frequently  form  a  raised  surface 
of  the  form  of  a  capital  H. 


FIG.  128. — Ceroplastes  floridensis,  adult  and  young 
females  on  Ilex,  natural  size  ;  a,  young  female,  en- 
larged :  3,  adult  female,  enlarged.  (From  thej  Au- 
thor's Report  for  1880.) 


FIG.  129. — Ceroplastes  cirripediformis. 
Adult  females,  natural  size  ;  a,  fe- 
male enlarged.  (From  the  Author's 
Report  for  1880.) 


^^Pulvindria. — This  genus  is  distinguished  from  Lecanium  only  by 


' 


144 


AN-  INTRODUCTION    TO   ENTOMOLOGY. 


the  fact  that  the  adult  female  excretes  a  large  cottony  mass  in  which 
the  eggs  are  laid.  Fig.  127  represents  Pulvindria  innumerdbilis, 
which  is  common  on  grape,  maple,  osage  orange,  and  other  plants. 

Ceropldstes.  —  The  species  belonging  to  this  genus  are  furnished 
with  a  thick  covering  of  waxy  material,  which  does  not,  however, 
adhere  closely  to  the  insect.  Only  two  species  have  been  found  in 
the  United  States.  Both  of  these  are  Florida  insects,  and  in  each  the 
waxy  covering  is  dirty-white  in  color.  The  most  common  species, 
C.  Floridensis  (Fig.  128),  infests  a  great  variety  of  plants  both  wild 
and  cultivated.  C.  cirripediformis  (Fig.  129)  is  not  very  common  ; 
it  infests  orange  and  quince.  It  is  a  beautiful  species,  as  the  waxy 
excretion  is  in  the  form  of  regular-shaped  plates. 


Sub-Family   III.  — 

The  Diasplnce  includes  those  species  of  scale-insects  that  form  a 
scale  composed  in  part  of  moulted  skins,  and  partly  of  an  excretion  of 
the  insect.  This  apparently  trivial  character  is  correllated  with  im- 
portant structural  characters,  which  mark  a  well-defined  group.  The 


FIG.  130.— Organs  of  the  last  segment  of  adult  females  of  the  Diaspinee.  a,  opening  of  oviduct; 
6,  anus  ;  d,  d,  ccphalo-lateral  groups  of  spinnerets  ;  «•,  *,  caudo-lateral  groups  of  spinnerets  ;  f ', 
lobes  ;  k,  spines  ;  /,  plates  (these  are  frequently  described  by  authors  as  spines).  (From  a  Report 
by  the  Author,  1881.) 

most  important  of  the  structural  characters  is  the  peculiar  form  of 
the  last  segment  of  the  body.  This  segment  is  highly  specialized 
for  the  excretion  and  manipulation  of  wax.  It  is  furnished  with 
many  openings  and  appendages.  These  vary  greatly  in  number  and 
form,  and  afford  good  characters  for  distinguishing  closely  allied 

*  Diasplnae,  Diaspis:  dia  (did,)  through;  aspis  (dcntis},  a  shield. 


PLATE   VI 


146  AN  INTRODUCTION    TO  ENTOMOLOGY. 

species.  Figure  130  represents  a  common  form  of  this  segment. 
But  these  special  characters  of  this  segment  are  not  presented  by  the 
larvae  till  after  the  first  moult,  nor  by  the  male  after  the  change  to 
pupa. 

The  following  account  of  the  metamorphoses  of  the  Diaspinae  is 
quoted  from  my  report  on  Scale-Insects  in  the  Annual  Report  of  the 
U.  S.  Department  of  Agriculture  for  1880. 

The  newly-hatched  scale-insect  is  oval  in  outline,  much  flattened,  furnished 
with  six  legs,  a  pair  of  antennae,  and  an  apparatus  for  sucking  the  juices  from 
plants.  (See  Plate  VI.  Fig.  2c,  young  of  Aspidiotus  ficus?)  At  this  stage  of 
its  existence  it  is  very  small,  a  mere  speck,  which  the  untrained  eye  could  only 
with  difficulty  detect.  By  means  of  a  lens,  however,  these  minute  creatures 
can  be  seen  crawling  in  all  directions  over  the  leaves  or  bark  of  an  infested 
tree.  After  wandering  for  a  time,  usually  but  a  few  hours  or  even  less,  the 
young  scale-insect  settles  on  some  part  of  the  plant,  inserts  its  beak,  and  draw- 
ing its  nourishment  from  the  plant,  begins  its  growth  at  the  expense  of  its  host. 
In  a  short  time  there  begins  to  exude  from  the  body  of  the  larva  fine  threads 
of  wax,  which  are  cottony  in  appearance.  The  excretion  of  this  wax  continues 
until  the  insect  is  completely  covered  by  it.  The  rate  at  which  this  excretion 
is  produced  varies  greatly.  Thus  larvae  of  the  red  scale  of  Florida  {Aspidiotus 
ficus),  which  were  only  one  day  old,  were  found  to  be  completely  covered  by  the 
cottony  mass  which  they  had  excreted  ;  while  the  larvae  of  Glover's  scale  (Myti- 
laspis  Gloverii}  did  not  become  entirely  covered  until  they  were  six  days  old. 
Sooner  or  later  the  larva  begins  to  excrete  a  pellicle,  which,  although  very 
thin,  is  dense  and  firm  in  texture.  The  mass  of  cottony  fibres  either  melts  or 
is  blown  away,  or,  as  in  certain  species  of  Aspidiotus,  a  portion  remains  as  a 
white  dot  or  ring  on  the  centre  of  the  scale.  After  a  period,  which,  in  several 
species  that  we  have  studied,  is  about  one-half  of  the  time  from  the  hatching  of 
the  larva  to  the  emerging  of  the  male,  or  one-third  of  the  time  from  the  birth 
of  the  female  to  the  date  at  which  she  begins  ovipositing,  the  larva  sheds  its 
skin.  In  some  species  this  does  not  take  place  until  after  the  beginning  of  the 
formation  of  the  permanent  scale,  and  in  such  cases  the  moulted  skin  adheres  to 
the  inner  surface  of  the  scale;  and  cannot  be  seen  while  it  is  in  its  normal  posi- 
tion on  the  plant.  This  is  true  of  many  species  belonging  to  the  genus  Aspidi- 
otus (A.  ficus,  A.  citri,  A.  perniciosus,  and  others).  In  these  species  the  position 
of  the  exuviae  is  indicated  by  a  nipple-like  prominence,  often  marked  by  a 
white  ring  or  dot,  which  is  the  remains  of  the  cottony  mass  first  excreted.  In 
other  species  the  moult  takes  place  before  the  beginning  of  the  excretion  of  the 
permanent  scale.  In  these,  the  larval  skin  is  plainly  visible  either  upon  the 
surface  of  the  scale,  as  in  certain  species  of  Aspidiotus  (A.  nerii,  Fig.  120),  and 
in  Diaspis  (Plate  VIII.  Fig.  \a,  20),  or  at  one  extremity,  as  in  Mytilaspis  (Plate 
X.  Fig.  irt).  Sometimes,  however,  the  larval  skin  is  covered  by  a  delicate  trans- 
parent layer,  which,  I  think,  is  the  melted  or  compacted  remains  of  the  cottony 
mass  excreted  by  the  young  larva  (Plate  X.  Fig.  20). 

The  change  which  the  larva  undergoes  at  this  moult  is  a  very  remarkable 
one,  appearing  to  be  a  retrogression,  instead  of  an  advancement  to  a  more 


HEMIPTERA.  147 

highly  organized  form,  as  is  the  rule  in  the  development  of  animals.  With  the 
skin  are  shed  the  legs  and  antennae.*  The  young  scale-insect  thus  becomes  a 
degraded  grub-like  creature,  with  no  organs  of  locomotion.  The  mouth-parts 
remain,  however,  in  a  highly  developed  state  and  are  well  fitted  to  perform 
their  functions.  This  apparatus  is  not  the  least  remarkable  thing  in  the 
structure  of  these  insects.  It  is  terminated  by  a  thread-like  organ,  which  is 
frequently  much  longer  than  the  body  of  the  insect,  and  is  composed  of  four 
delicate  hair  like  bristles.  By  means  of  this  organ  the  insect  is  firmly  attached 
to  the  plant,  and  draws  its  nourishment  therefrom.  From  this  stage  the  devel- 
opment of  the  sexes  differs. 

The  second  and  last  moult  of  the  female  takes  place,  in  those  species  which 
we  have  studied  most  carefully,  when  she  is  about  twice  as  old  as  when  the 
first  moult  occurred.  The  change  in  appearance  at  this  moult  presents  nothing 
remarkable.  The  second  cast  skin  is  joined  to  the  first,  and  with  it  forms  a 
part  of  the  scale  which  covers  the  body  of  the  insect.  Sometimes,  as  in  the 
genus  Uhleria  (Plate  VII.  Fig.  9),  this  moulted  skin  is  very  large  and  constitutes 
the  greater  part  of  the  scale;  but  more  commonly  the  exuviae  form  but  a  small 
proportion  of  the  scale,  the  greater  part  of  it  being  excreted  subsequently  to 
the  second  moult.  Soon  after  the  second  moult  of  the  females  takes  place  the 
adult  males  emerge,  and  doubtless  the  impregnation  of  the  females  occurs  at 
once.  After  this,  the  body  of  the  female  increases  in  size,  becoming  distended 
with  eggs.  The  oviposition  takes  place  gradually,  and,  in  those  species  that  we 
have  studied,  begins  when  the  female  is  about  three  times  as  old  as  when  the 
first  moult  occurred.  The  eggs  are  deposited  beneath  the  scale,  the  body  of  the 
female  gradually  shrinking  and  thus  making  room  for  them.  (See  Plate  X. 
Figs.  \b  and  2c.)  Some  species,  however,  are  viviparous. 

The  male  scale-insect  during  the  early  part  of  its  larval  life  is  indistinguish- 
able from  the  female.  The  first  moult  occurs  at  the  same  time  and  is  accom- 
panied by  a  similar  change,  the  male  larva,  like  the  female,  losing  its  legs  and 
antennas.  The  second  moult  is  also  synchronous  with  the  second  moult  of  the 
female ;  but  here  the  similarity  in  form  between  the  two  sexes  ceases.  Even 
before  this  moult  takes  place  there  may  be  observed  the  formation  of  rudiment- 
ary limbs  beneath  the  transparent  memberless  skin  of  the  larva;  and  after  this 
skin  is  shed,  the  male,  now  in  the  pupa  state,  differs  remarkably  from  the 
female.  The  male  pupa  has  long  antennae,  and  its  legs  and  wings,  although  in 
a  rudimentary  state,  are  very  large.  The  duration  of  the  pupa  state  in  those 
species  which  we  have  bred,  in  short,  lasting  but  a  few  days;  and  then,  after  a 
third  casting  of  the  skin,  the  adult  male  appears. 

The  outline  figures  on  Plates  IV.,  VI.,  and  IX.  represent  the  insect  in 
this  stage.  The  anterior  wings,  though  very  delicate,  are  large,  and  enable 
the  male  to  fly  readily.  The  posterior  wings  are  represented  only  by  a  pair  of 
halteres.  These  insects  resemble  in  this  respect  the  flies,  gnats,  and  other 
insects  belonging  to  the  order  Diptera,  or  two-winged  insects.  The  posterior 
end  of  the  body  is  furnished  with  a  style,  which  is  sometimes  nearly  as  long  as 
the  remainder  of  the  body,  and  is  the  external  organ  of  reproduction.  As  our 
figures  represent  only  a  dorsal  view,  the  most  remarkable  character  of  the 

*  Rudiments  of  antennse  are  sometimes  retained,  as  in  certain  species  of  Mytilaspis. 


PLATE  VII. 


VC7 


Scales  of  the  Diaspina,  from  camera-lucida  drawings,  i,  Aspidiotus  ficus,  female  ;  ia,  male  of 
same  ;  2,  Aspidiotus  nerii,  female  ;  2<z,  male  of  same;  3,  Diaspis  rosa>,  female;  3«,  male  of 
same;  4,  Chionaspis  furfurus,  female  ;  4«,  male  of  same;  5,  Mytilaspis  pomorum,  female  ; 
5«,  male  of  same;  6,  Parlatoria pergandii,  female;  6a,  male  of  same;  7,  Parlatoria  Proteus, 
female;  7<i,  male  of  same;  8,  Parlatoria  zizyphi,  female  ;  9,  Uhleria  camellia;;  10,  Aspidi- 
otus ?  parlatoroides,  female  ;  n,  Chionaspis  ?  biclavis. 


HEMIPTERA,  149 

adult— the  supplementary  eyes  which  takes  the  place  of  the  mouth- parts— is 

not  shown. 

The  genera  of  the  Diaspinae  are  characterized  chiefly  by  the  form 
of  the  scales,  and  the  position  of  the  moulted  skins  or  exuviae  upon 
them.  In  the  use  of  these  characters  it  is  necessary  to  distinguish 
the  sex  of  the  individual  by  which  a  given  scale  was  made.  This 
can  be  done  as  follows:  In  the  scale  of  the  fully  developed  female 
there  are  two  moulted  skins,  while  in  that  of  the  male  there  is  but 
one.  Our  genera  can  be  separated  by  the  following  table  :* 

A.   Scale  of  female  circular  with  the  exuviae  either  central  or  more  or  less 
nearly  marginal. 

B.  Scale  of  male  but  little  elongated,  with  the  exuviae  more  or  less  central ; 
scale  usually  resembling  that  of  the  female  in  color  and  texture  (Plate 
VII.  Fig.  la  and  20).  ASPIDIOTUS. 

BB.  Scale  of  male  elongated,  with  the  exuviae  at  one  extremity. 
C.  Scale  of  male,  white  and  carinated  (Plate  VII.  Fig.  3*7).  DIASPIS. 

CC.  Scale   of   male,  not  white   and  with   no  central   carina   (Plate  VII. 
Fig.  &?).  PARLATORIA. 

AA.  Scale  of  female  elongated,  with  the  exuviae  at  one  extremity. 
D.  Exuviae  small. 

E.  Scale  of  male,  white  and  carinated  t  (Plate  VII.  Fig.  4*);   last 

segment  of  female  with  five  groups  of  spinnerets.  CHIONASPIS. 

EE.  Scale  of  male  white,  but  not  carinated;  female  with  eight  groups 

of  spinnerets.  POLIASPIS. 

EEE.  Scale  of  male  similar  in  form  to  that  of  the  female  (Plate  VII. 

Fig.  s«).  MYTILASPIS. 

DD.  Exuviae  large. 

F.  Two  moulted  skins  visible  on  the  scale  of  the  female  (Plate  VII. 

Fig.  7,  8).  PARLATORIA. 

FF.  "second  skin  covered  by  a  secretion  (Plate  I.  Fig.  9).       UHLERIA. 

The  accompanying  illustrations,  from  my  report  on  scale-insects 
in  the  Report  of  the  U.  S.  Dept.  of  Agriculture  for  1880,  will  enable 
the  reader  to  recognize  the  more  important  species  of  this  sub-family. 

Aspidiotus.—™*  is  the  largest  genus  of  the  Diaspinae ;  more  than 
twenty  species  have  been  observed  in  the  United  States.     The  one 
which  has  done  the  greatest  injury  to  citrus  fruits  on  the 
coast  is  the  Red  Scale  of  California,  Aspidwtus  aurdntii  (Plate  VI.  i). 
Closely  allied  to  this  is  the  Red  Scale  of  Florida,  A.ficus  (. 

*  From  the  author's  Second  Report  on  Scale-Insects  ;  published  in  the  Second  Report 
of  the  Cornell  University  Experiment  Station.     Ithaca,  N.  Y.,  1883. 

f  In  Chionaspis  ortholobis  the  scale  of  the  male  is  not  carmated. 
willow  in  California. 


PLATE    VIII. 


±0. 


11 


HEMIPTERA.  jg! 

2).  This  also  infests  oranges ;  but  its  injuries  are  overshadowed  in 
Florida  by  those  of  other  scale-insects;  A.  nerii  (Fig.  120)  is  the 
common  white  scale,  which  occurs  on  a  great  variety  of  plants.  It 
is  an  imported  insect ;  but  I  have  collected  it  throughout  our  country 
from  the  Great  Lakes  to  the  Gulf  of  Mexico,  and  from  the  Atlantic 
to  the  Pacific ;  in  the  colder  parts  of  the  United  States  it  is,  next  to 
the  mealy-bugs  and  Lecanium,  the  most  common  Coccid  on  house- 
plants.  In  northern  California,  and  especially  in  the  Santa  Clara 
Valley,  is  found  A.  perniciosus;  this  is  a  circular,  grayish  scale  which 
infests  nearly  all  of  the  deciduous  fruit-trees  grown  in  that  State.  It 
is  the  most  destructive  of  the  scale-making  Coccids;  and  before  the 
fruit-growers  awoke  to  the  importance  of  fighting  it,  it  came  near 
destroying  the  orchards  of  that  section. 

Didspis.— Our  commonest  representative  of  this  genus  is  Didspis 
rosce  (Plate  VIII.  i);  this  is  a  snowy-white  scale,  which  occurs 
abundantly  on  neglected  roses;  I  have  found  it  also  on  raspberry, 
and  blackberry  bushes.  Didspis  carueli  (Plate  VIII.  2)  is  common 
in  some  localities  on  Juniper  and  allied  plants. 

Chiondspis. — The  common  white  scale  of  pear  and  apple  is  Chi- 
onaspis  ffirfurus  (Plate  IX.  i).  Another  common  species  which 
occurs  throughout  the  United  States  upon  the  leaves  of  pine  and 
spruce  is  C.  pinifolii  (Plate  IX.  2).  C.  eudnymi  (Plate  VIII.  3)  in- 
fests Euonymus ;  it  is  remarkable  for  having  the  scale  of  the  female 
of  a  dirty  blackish-brown  color,  instead  of  white,  as  is  the  rule  in  this 
genus.  The  common  white  scale  of  willow  is  C.  sdlicis. 

Mytildspis. — To  this  genus  belong  some  of  the  best  known  Coc- 
cids. Of  those  that  occur  on  plants  in  the  open  air,  only  three 
American  species  have  been  recognized.  Two  of  these  abound  on 
oranges.  One  of  the  orange  species,  M.  gloverii,  (Plate  X.  2,)  can  be 
easily  recognized  by  the  very  narrow  form  of  the  scale,  and  the  fact 
that  the  eggs  are  laid  in  two  rows  beneath  the  scale  (Plate  X.  Fig.  2,  c]. 
In  the  other  orange  species,  M.  citricola,  (Plate  X.  i,)  the  scale  of  the 
female  is  much  wider,  and  the  eggs  are  massed  irregularly  beneath 
the  scale.  The  Oyster-shell  Bark-louse  of  the  Apple,  M.  pomorum, 
is  distinguished  from  M.  citricola  only  by  minute  characters.  The 
figure  just  referred  to  would  serve  equally  well  for  this  species,  ex- 
cept that  it  does  not  occur  on  the  orange.  It  is  the  most  common 
scale  of  the  apple  in  all  parts  of  the  United  States  in  which  that  tree 
grows  ;  it  infests  also  a  great  variety  of  other  plants. 

The  food-plants  of  the  species  figured  on  Plate  VII.,  and  not 
named  above,  are  as  follows  :  Parlatoria  pergdndii occurs  on  Florida 


PLATE    IX. 


HEMIPTERA.  153 

oranges.  Parlatoria  proteus  has  been  found  only  on  exotic  plants 
in  conservatories.  Parlatoria  zizyphi  is  an  exotic  species  which  is 
often  found  on  imported  oranges.  Uhleria  camtllice  is  a  trouble- 
some pest  of  the  camellia  in  conservatories.  Aspidiotus  parlato- 
roidcs  infest  the  Bay  Tree  in  Florida.  And  Chiondspis  bicldvis  is  a 
remarkable  species,  which  I  found  burrowing  beneath  the  epidermal 
layer  of  certain  exotic  plants  in  the  conservatories  at  Washington. 

Family    III.  —  ALEYRODID.E.* 

(A  ley  r  odes.) 

The  insects  of  the  genus  Aleyrodes  were  for  a  long  time  classed 
with  the  Coccidae.     In  their  immature  state  they  are  scale-like  in 
form  (Fig.   131),  and   often   somewhat  resemble  certain  species  of 
Lecanium.     But  the  mature  insects  differ  so 
much  from  Coccids  that  the  genus  has  been 
separated  as  a  distinct  family.     They  are  very 
small    insects  ;    the   species  with  which   I  am 
acquainted  have  an  expanse  of  wings  of  about 
three    millimeters.      Both    sexes   are  winged  ; 
and,    as   with    other    Hemiptera    except    the 
Coccids,  there  are  two  pairs  of  wings.     In  the 
adult  state,  all  the  species  are  of  nearly  the          FIG.  131.- 
same  color;    the  wings  are  white,  sometimes 

spotted  ;  the  body  is  usually  yellowish,  sometimes  pinkish,  and  more 
or  less  spotted  with  black.  The  most  striking  character  presented 
by  the  adults,  in  addition  to  the  fact  that  both  sexes  are  winged, 
and  each  has  two  pairs  of  wings,  is  the  presence  of  a  whitish  powder 
with  which  the  wings  and  body  are  covered.  It  is  this  character 
which  gives  the  name  to  the  genus. 

With  the  adults  the  eyes  are  reniform,  and  generally  divided 
into  two  portions,  separated  by  a  membrane  ;  in  some  species  they 
are  more  or  less  rounded  or  triangular.  Above  each  eye  there  is  a 
minute  ocellus.  The  rostrum  is  stout,  and  composed  of  three  seg- 
ments. The  antennae  are  seven-jointed.  The  wings  in  repose  are 
carried  nearly  horizontally.  The  first  pair  are  the  larger,  and  are 
traversed  by  two  veins  ;  the  first  vein,  which  passes  through  the  mid- 
dle of  the  wing,  is  much  the  larger;  the  hind  wings  have  only  a 
single  vein. 


AleyrSdidse,  AleyrOdes:  ahurodes  (dXevpvSet),  like  flour. 


PLATE   X. 


HEMIPTERA. 


155 


Owing  to  their  small  size  and  similarity  in  color,  it  is  difficult  to 
distinguish  the  different  species  of  Aleyrodes  in  the  adult  state. 
But  the  immature  scale-like  forms  present  considerable  differences. 
The  most  common  form  that  I  have  met  is  very  flat,  nearly 'circular 
in  outline,  and  furnished  with  a  beautiful  white  fringe  (Fig.  131); 
this  fringe  is  composed  of  parallel  fibres,  which  radiate  from  the 
margin  of  the  body  ;  and  its  white  color  contrasts  strongly  with  the 
dark  color  of  the  insect.  The  segmentation  of  the  body  is  often 
represented  by  prominent  wrinkles,  which  give  the  insect  a  minia- 
ture resemblance  to  the  fossils  known  to  geologists  as  Trilobites. 
Sometimes  the  fringe  of  excretion  is 
wanting;  and  in  a  common  species  on 
maple,  the  excretion  from  the  margin  of 
the  body,  instead  of  extending  laterally 
and  forming  a  fringe,  is  directed  towards 
the  leaf  upon  which  the  insect  rests, 
and  thus  the  body  is  lifted  away  from  FlG-  *•&•— Aleyrodes  on  maple, 
the  leaf,  and  perched  upon  an  exquisite  palisade  of  white  wax 
(Fig.  132). 

The  American  species  of  this  family  have  not  been  studied.  In 
case  any  of  them  become  destructive  to  vegetation,  they  can  proba- 
bly be  destroyed  by  strong  alkaline  solutions,  as  are  Coccids. 


Family  IV.— APHIDID.E.* 
(Plant-lice^ 

The  plant-lice  are  well-known  insects ;  they  infest  nearly  all 
kinds  of  vegetation  in  all  parts  of  the  country.  Our  most  common 
examples  are  minute,  soft-bodied,  green  insects,  with  long  legs  and 
antennae,  which  appear  on  various  plants  in  the  house  and  in  the 
field.  Among  our  common  species  are  both  winged  and  wingless 
forms.  There  are  a  great  number  of  species,  nearly  all  of  which 
are  of  small  size.  The  bodies  of  our  largest  species  measure  only  6 
or  7  mm.  (0.24  or  0.25  inch)  in  length. 

The  body  is  usually  more  or  less  pear  shaped.  The  winged 
forms  have  two  pairs  of  delicate,  transparent  wings.  These  are  fur- 
nished with  a  few  simple  veins ;  but  the  venation  is  more  extended 

*  Aphldidze,  Aphis:  perhaps  from  aphysso  (dfivcro-w),  to  drink  up  liquids. 


156  AN  INTRODUCTION    TO   ENTOMOLOGY. 

than  in  either  of  the  two  preceding  families.  The  first  pair  of  wings 
is  larger  than  the  other ;  and  the  two  wings  of  each  side  are  usually 
connected  by  a  compound  hooklet.  The  beak  is  two-jointed,  and 
varies  greatly  in  length  ;  sometimes  it  is  longer  than  the  body.  The 
compound  eyes  are  prominent ;  and  ocelli  are  also  usually  present. 
The  antennae  are  from  three-  to  seven-jointed.  On  the  dorsal  aspect 
of  the  sixth  abdominal  segment  there  is,  in  many  species,  a  pair  of 
tubes,  through  which  a  sweet,  transparent  fluid  is  excreted.  In 
some  genera  these  organs  are  merely  perforated  tubercles ;  while  in 
still  other  genera  they  are  wanting. 

The  fluid  which  is  excreted  through  the  abdominal  tubercles  is 
the  substance  known  as  honey-dew.  It  is  sometimes  produced  in 
such  quantities  that  it  forms  a  glistening  coating  on  the  leaves  of 
the  branches  below  the  plant-lice,  and  stone  walks  beneath  shade- 
trees  are  often  densely  spotted  with  it.  This  honey-dew  is  fed  upon 
by  bees,  wasps,  and  ants.  The  bees  and  wasps  take  the  food  where 
they  find  it,  paying  little,  if  any,  attention  to  its  source.  But  the 
ants  recognize  in  the  plant-lice  useful  auxiliaries,  and  often  care  for 
them  as  man  cares  for  his  herds.  This  curious  relationship  will  be 
more  fully  discussed  under  the  head  of  ants. 

In  addition  to  honey-dew,  many  Aphids  excrete  a  white  sub- 
stance. This  may  be  in  the  form  of  a  powder,  scattered  over  the 
surface  of  the  body,  or  it  may  be  in  large  flocculent  or  downy 
masses ;  every  gradation  between  these  forms  exists. 

The  plant-lice  are  remarkable  for  their  peculiar  mode  of 
development.  The  various  species  differ  greatly  in  the  details 
of  their  transformations ;  but  the  following  generalizations  can  be 
made. 

At  some  period  eggs  are  produced  by  impregnated  females. 
This  ordinarily  occurs  in  the  autumn  ;  in  which  case  the  eggs  do  not 
hatch  till  the  following  spring.  From  the  fact  that  these  eggs  are 
fertilized,  they  are  frequently  referred  to  as  true  eggs,  in  contradis- 
tinction to  pseudova,  described  later.  These  true  eggs  are  also 
known  as  winter  eggs. 

From  the  winter  eggs  there  hatch  in  the  spring  a  generation  of 
Aphids  in  which  there  is  no  distinction  of  sex.  All  are  females  ; 
and  each  has  the  power  of  reproducing  without  the  intervention  of  a 
male.  Such  reproduction  is  termed  agamic  *  reproduction,  or  repro- 
duction by  budding.  And  this  term  is  also  applied  to  the  individu- 

*  Agamic:  a  (a),  without;  gamos  (yd^io^),  marriage. 


HEMIPTERA  i$j 

als  that  reproduce  in  this  way.  Usually,  the  agamic  generation  pro- 
duced  by  the  winter  eggs  is  wingless.  The  agamic  female  which 
hatches  from  a  winter  egg,  being  the  starting  point  from  which  arise 
the  generations  that  intervene  between  this  egg  and  the  production 
of  other  true  eggs,  is  termed  the  stem-mother. 

The  offspring  of  the  stem-mothers  are  wingless  or  winged  or 
both,  and  are  agamic.  In  many  cases  they  are  born  alive.  This 
can  be  seen  by  examining  almost  any  colony  of  plant-lice  during  the 
summer-time.  While  an  agamic  mother  is  unconcernedly  feeding 
or  walking  about,  it  may  be  giving  birth  to  a  young  louse;  the  lat- 
ter can  be  seen  with  the  unaided  eye,  but  better  with  a  lens,  emerg- 
ing from  the  caudal  end  of  its  mother,  tail  first,  and  kicking  vigor- 
ously, even  before  its  head  has  been  delivered.  In  other  cases,  the 
agamic  form  produces  egg-like  bodies,  which  are  termed  pseudova,  to 
distinguish  them  from  the  fertilized  or  true  eggs.  And,  in  still  other 
cases,  they  produce  living  young,  which  are  enveloped  in  a  pellicle, 
from  which  they  emerge  in  the  course  of  a  few  minutes ;  such  an 
enveloping  pellicle  with  its  enclosed  young  is  also  termed  a  pseudo- 
vum. 

The  number  of  agamic  generations  that  may  follow  without  the 
intervention  of  sexual  forms  varies  with  different  species,  and,  in 
some  cases  at.  least,  varies  in  the  same  species,  depending  upon  tem- 
perature and  other  conditions.  Thus  Kyber,  in  the  early  part  of 
this  century,  succeeded,  by  keeping  the  insects  in  a  warm  room,  in 
raising  a  series  of  agamic  generations  of  two  species  of  Aphids, 
which  extended  through  four  years  without  the  intervention  of  sex- 
ual forms. 

As  already  indicated,  the  agamic  generations  are  of  two  forms, 
wingless  and  winged.  Each  of  these  has  a  peculiar  function  in  the 
economy  of  the  species.  The  wingless  generations,  which  are  usu- 
ally the  more  numerous,  by  their  great  fecundity  provide  for  the 
enormous  and  rapid  multiplication  of  individuals,  which  is  so  charac- 
teristic of  these  insects.  But  this  great  increase  of  individuals  would 
be  disastrous  to  the  species,  by  the  destruction  of  the  infested 
plants  and  the  consequent  starving  of  the  insects,  were  it  not  sup- 
plemented by  other  powers.  We  find,  therefore,  interspersed  among 
these  wingless  sedentary  generations,  generations  which  are  winged 
and  migrating.  Thus  the  spread  of  the  species  is  provided  for. 

Generally  on  the  setting  in  of  cold  weather,  or  in  some  cases  on 
the  failure  of  nourishment,  the  weather  being  still  warm,  there  is 
produced  a  generation  including  individuals  of  both  sexes.  The 
ii 


158  AN  INTRODUCTION   TO   ENTOMOLOGY. 

males  may  be  either  winged  or  wingless  ;  but,  so  far  as  is  known,  the 
females  that  pair  with  the  males  are  always  wingless.  These 
females,  after  becoming  impregnated,  produce  the  winter  eggs;  thus 
is  completed  the  cycle  of  changes  through  which  the  species  passes. 
In  many  cases,  at  least,  the  individuals  of  the  agamic  generation 
that  immediately  precedes  the  sexual  one  produce  but  few  pseudova  ; 
from  these  pseudova  the  sexual  individuals  emerge,  not  as  larvae, 
but  as  fully  developed  individuals,  ready  to  pair  and  reproduce  ;  in 
fact,  in  the  cases  referred  to,  the  sexual  individuals  have  the  mouth- 
parts  in  a  rudimentary  state,  and  take  no  nourishment.  In  many 
species,  the  impregnated  female  produces  a  single  egg,  which  is 
nearly  as  large  as  the  insect  herself ;  frequently  this  egg  is  not 
laid,  but  remains  throughout  the  winter  in  the  dry  skin  of  the  dead 
parent. 

Agamic  Aphides  may  hibernate,  and  may  coexist  with  the  sexual 
generation  of  the  same  species. 

From  the  above  generalizations  it  will  be  seen  that  a  single 
species  of  plant-louse  may  present  three  distinct  forms :  first,  a 
sedentary,  agamic,  wingless  form,  furnished  with  mouth-parts ; 
second,  a  migrating,  agamic  form,  which  is  winged  and  furnished 
with  mouth-parts ;  third,  a  sexual  form,  of  which  the  females  are 
wingless,  while  the  males  may  be  either  winged  or  wingless ;  in  cer- 
tain cases,  at  least,  the  sexual  forms  are  mouthless. 

There  is  unfortunately  a  generalization  in  most  of  the  text-books 
on  entomology  that  is  incorrect.  It  is  that  the  winged  generation  is 
produced  only  on  the  approach  of  cold  weather,  and  that  this  gen- 
eration is  the  sexual  one. 

Plant-lice  are  often  very  destructive  to  vegetation  ;  they  appear, 
however,  to  be  more  liable  to  attack  unhealthy  plants  than  those 
that  are  in  good  condition.  The  best  method  of  destroying  these 
pests  is  by  spraying  with  a  strong  solution  of  soap,  or  with  kerosene 
emulsion.  (See  Chapter  XIV.)  As  plant-lice  draw  their  nourish- 
ment from  below  the  surface  of  the  plants  they  infest,  they  are  not 
injured  by  the  application  of  poisons  to  the  plants. 

The  Aphididae  comprises  four  sub-families  ;  the  following  table 
for  separating  these  sub-families  is  published  by  Dr.  Thomas,  in  the 
Eighth  Report  of  the  State  Entomologist  of  Illinois.  It  is  necessary 
here  to  give  the  names  applied  to  the  veins  of  the  wings,  as  some  of 
them  are  used  in  this  table.  The  principal  vein  of  the  front  wing, 
that  which  extends  from  the  base  to  near  the  tip  of  the  wing,  (Fig. 


HEMIPTERA.  j  *Q 

133,^)  is  the  subcostal  or  submarginal  vein.  The  distal  end  of 
this  vein  becomes  widened,  and  ex- 
tends to  the  margin  of  the  wing ;  this 
part  of  it  is  the  stigma  (st).  From  the 
stigma,  a  curved  vein  extends  to  the 
tip  of  the  wing;  this  is  the  stigmatic 
or  fourth  vein.  From  the  submarginal 
vein  there  branch  two  or  three  veins 
(in  addition  to  the  stigmatic  vein), 
which  extend  across  the  disk  of  the 
wing;  these  are  the  first,  second,  and  FIG.  i33.-wings of  piant-iouse. 

third   discoidal   veins.     The    third    dis- 

coidal  vein  is  sometimes  forked.  '"'"The  veins  of  the  hind  wing,  so 
far  as  they  are  present,  are  named  in  a  similar  manner. 

A.  Winged  form  known;    species  not  subterranean,  except  in  a  few  cases 
where  there  are  dimorphic  forms. 

B.  Front  wings  with  three  discoidal  veins  ;  antennae  of  the  winged  individu- 
als, and  generally  of  the  apterous  individuals,  six-  or  seven-jointed. 
C.  Front  wings  with  the  third  discoidal  vein  twice  forked  (except  in  Tox- 
optera,   which,    however,    has  well-developed  honey-tubes) ;    posterior 
wings  with  two  discoidal  veins;  honey-tubes  various.         4.  APHIDIN^E. 
CC.  Third  discoidal  vein  with  one  fork  or  simple  ;  posterior  wings  with 
one    or    two    oblique    veins ;    honey-tubes     tuberculiform    or    want- 
ing. 3.  PEMPHIGIN^:. 
B.  Front  wings  with  but  two  discoidal  veins,  the  third  being  absent ;  an- 
tennae never  more  than  five-jointed,  sometimes  but  three-jointed. 

2.  CHERMESIN^E. 

AA.  Permanently  apterous  ;  at  least  no  winged  form  has  been  observed  :  chiefly 
subterranean,  residing  on  the  roots  of  plants.  i.  RHIZOBIIN^E. 

Sub-Family  I.— RHIZOBIIN.E.* 

As  indicated  in  the  table  above,  this  sub-family  has  been  erected 
for  certain  genera  in  which  no  winged  forms  are  known.  It  is  pos- 
sible that  some  of  the  insects  placed  here  are  merely  the  degraded 
wingless  generation  of  species  which  have  also  higher  developed 
forms  with  wings,  and  which  pertain  to  some  one  of  the  three  higher 
sub-families. 

The  Rhizobiincz  live  in  the  ground  upon  the  roots  of  plants. 
Our  best  known  representative  is  the  Lettuce  Earth-louse,  Rhizobius 
lactucce.  This  occurs  on  the  roots  of  lettuce,  often  in  great  num- 

*  Rhizobilnse,  Rhizobius;  rhiza(pi^a),  root;  bios  (fiioS),  life. 


i6o 


AN  INTRODUCTION    TO  ENTOMOLOGY. 


bers.  The  mature  lice  measure  2  mm.  (0.08  inch)  in  length.  They 
are  oval,  of  a  dull  white  color,  with  dusky  legs  and  antennae,  and 
with  the  body  dusted  over  with  a  white  powder. 

Other  species  of  this  sub-family  are  found  on  roots  of  grasses  or 
herbaceous  plants,  and  usually  accompanied  by  ants. 

Sub-Family  II. — CHERMESIN^E.* 

The  Chermesince  includes  those  genera  of  plant-lice  in  which  the 
front  wings  have  only  two  discoidal  veins ;  the  antennas  are  from 
three-  to  five-jointed. 

This  sub-family  is  represented  by  two  common  genera,  Chermes 
and  Phylloxera.  In  Chermes  the  antennae  are  five-jointed,  while  in 
Phylloxera  they  are  only  three-jointed. 

Chermes. — The  most  common  species  of  this  genus  is  the  Pine 
Blight,  Chermes  pinicorticis.  This,  in  its  most  conspicuous  form,  ap- 
pears as  patches  of  white,  flocculent,  down-like  matter  on  the  smooth 
bark  of  young  white-pine  trees.  Beneath  these  patches  of  white 
substance  the  very  minute  young  lice  can  be  found.  The  winged 
generation  appears  in  early  summer.  A  closely  allied  species,  Cher- 
mes abieticolens,  infests  the  terminal  shoots  of  spruce,  producing 
large  swellings. 

Phylloxera. — This  genus  contains  many  species;    one  of  them, 

Phylloxera  vastdtrix,  has 
attracted  so  much  atten- 
tion by  the  great  extent 
of  its  ravages  that  it  is 
often  referred  to  as  the  Phyl- 
loxera. It  is  more  properly 
termed  the  Grape  Phyllox- 
era. We  have  space  for  only 
a  brief  account  of  the  his- 
tory of  this  species. 

The  presence  of  this  in- 
sect is  manifested  by  the 
vines  in  two  ways :  first,  in 
the  case  of  certain  species  of 
grapes,  there  appear  upon 
the  lower  surface  of  the 
leaves  fleshy  swellings,  which  are  more  or  less  wrinkled  and  hairy 
(Fig.  134);  these  are  hollow  galls,  opening  upon  the  upper  surface 


FIG.  134.— Leaf  of  grape  with  galls  of  Phyllo 
(From  Riley.) 


*  Chermeslnae,  Chermes:  Arab,  ker/nes,  Skt.  krimi,  a  worm. 


HEMIPTERA. 


161 


of  the  leaf,  and  containing  a  wingless  agamic  plant-louse  and 
her  eggs ;  second,  when  the  fibrous  roots  of  a  sickly  vine  are 
examined,  we  find,  if  the  disease  is  due  to  this  insect,  that  the 
minute  fibres  have  become  swollen  and  knotty;  or,  if  the  disease 
is  far  advanced,  they  may  be  entirely  decayed.  Upon  these  root- 
swellings  we  also  find  an  agamic,  wingless,  egg-laying  plant-louse, 
the  author  of  the  mischief. 

The  insects  found  upon  the  roots  differ  slightly  from  those  found 
within  the  galls ;  but  their  specific  identity  is  now  generally  accept- 
ed. A  careful  study  of  this  insect  has  revealed  still  other  forms. 
So  that  now  we  can  say  that  the  species  is  presented  to  us  under 
the  three  distinct  forms  described  below. 

Of  the  first  form  there  are  two  types :  one,  the  root-inhabiting 
type,  which  causes  the  knots  on  the  roots ;  second,  the  gall-inhabit- 
ing type,  which  produces  the  galls  upon  the  leaves.  The  gall-inhab- 
iting type  is  simply  a  dimorphic  form,  which  does  not  constitute  an 
essential  part  in  the  cycle  of  changes  through  which  the  species  must 
pass.  It  only  appears  when  the  insect  infests  certain  species  of  grapes. 

The  following  epitomized  account  of  the  life-history  of  this  spe- 
cies is  condensed  from  Dr.  C.  V.  Riley's  Sixth  and  Seventh  Mis- 
souri Entomological  Reports: 


The  Grape  Phylloxera  hibernates  upon  the  roots  of  the  grape, 
mostly  as  a  young  larva  of  the  first  or  sedentary,  agamic,  wingless 
form  (Fig.  135).  With  the  renewal  of  vine-growth  in  the  spring, 


1 62 


AN  INTRODUCTION    TO   ENTOMOLOGY. 


this  larva  moults,  rapidly  increases  in  size,  and  soon  commences  lay- 
ing eggs.  These  in  due  time  give  birth  to  young,  which  soon 
become  agamic,  egg-laying  mothers,  like  the  first ;  and,  like  them, 
always  remain  wingless.  Five  or  six  generations  of  these  parthen- 


FIG.  136. — Phylloxera,  root-inhabiting  form,  a  shows  a  healthy  root ;  £,  one  on  which  the  lice  are 
working,  representing  the  knots  and  swellings  caused  by  their  punctures;  <r,  a  root  that  has 
been  deserted  by  them,  and  where  the  rootlets  have  commenced  to  decay  ;  d,  d,  d.  shows  how 
the  lice  are  found  on  the  larger  roots  ;  e,  female  nymph,  dorsal  view  ;  f,  same,  ventral  view  ;  g, 
winged  female,  dorsal  view  ;  h^  same,  ventral  view  ;  z,  magnified  antenna  of  winged  insect ;  /, 
side  view  of  the  wingless  female,  laying  eggs  on  roots  ;  k  shows  how  the  punctures  of  the  lice 
cause  the  larger  roots  to  rot.  (From  Riley.) 

ogenetic,  egg-bearing,  wingless  mothers  follow  each  other,  when 
(about  the  middle  of  July,  in  the  latitude  of  St.  Louis)  some  of 
the  individuals  begin  to  acquire  wings.  Thus  is  produced  the  second, 
or  migrating,  agamic,  winged  form  (Fig.  136).  These  issue  from 
the  ground  while  yet  in  the  pupa  state ;  as  soon  as  they  have  ac- 


HEMIPTERA. 


163 


quired  wings,  they  rise  in  the  air  and  spread  to  new  vineyards,  where 
they  lay  their  eggs,  usually  in  the  down  of  the  under  sides  of  the 
leaves.  Each  individual  of  this  generation  lays  from  three  to  five, 
and  sometimes  as  many  as  eight  eggs.  These  eggs  are  of  two  sizes; 
the  smaller,  which  produce  males,  are  about  three-fourths  the  size 
of  the  larger,  which  produce  females.  From  these  eggs  are  hatched, 
in  the  course  of  a  fortnight,  the  third,  or  wingless,  sexual  form.  It  is 
a  very  remarkable  fact  that  this  form  emerges  from  the  egg  not  as 
larvae  but  as  fully  developed  inq!ividuals.  These  sexual  individuals 
are  born  for  no  other  purpose  than  the  reproduction  of  their  kind,  and 
are  without  means  of  flight,  or  of  taking  food.  After  pairing,  the  body 
of  the  female  enlarges  somewhat  and  she  is  soon  delivered  of  a  solitary 
egg.  This  impregnated  egg  gives  birth  to1  a  young  louse,  which  devel- 
ops into  the  first  or  sedentary,  agamic,  wingless  form ;  and  thus  re- 
.commences  the  cycle  of  changes  through  which  the  insect  passes. 

It  has  been  discovered  that  sometimes  the  first  form,  during  the 
latter  part  of  the  season,  lays  a  few  eggs,  which  are  of  two  sizes,  like 
those  of  the  second  form,  and  like  those  also  produce  males  and 
females.  These  males  and  females  are  precisely  like  those  born  of 
the  winged  form,  and  like  them  produce  the  solitary  impregnated 
egg.  Thus  the  interesting  fact  is  established  that  even  the  winged 
form  is  not  essential  to  the  perpetuation  of  the  species. 


^ 

IS  ^iews T'lhe?  aSen'na ;  Jher  two-jointed  tarsus.  Natural  sizes  indicated  ats.des.  (from  R.lcy.) 

If  to  the  above  account  we  add  that  occasionally  individuals 
abandon  their  normal  underground  habit,  and  form  galls  upon  the 
leaves  of  certain  varieties  of  grape-vine  (Fig.  137),  we  have,  in  a 
general  way,  the  whole  natural  history  of  the  species. 


164  AN  INTRODUCTION   TO  ENTOMOLOGY. 

Owing  to  the  great  injury  which  the  species  has  done  to  the  vine- 
yards of  France,  hundreds  of  memoirs  have  been  published  regard- 
ing it.  But,  as  yet,  no  satisfactory  means  of  destroying  it  has  been 
discovered.  The  difficulty  lies  in  the  fact  that  the  insecticide  must 
be  one  that  can  penetrate  the  ground  to  the  depth  of  three  or  four 
feet,  reaching  all  of  the  fibrous  roots  infested  by  the  insect.  It 
must  be  a  substance  that  can  be  cheaply  applied  on  a  large  scale  ; 
and  it  must  also  be  something  that  will  kill  the  insect  without  injury 
to  the  vine. 

Where  the  vineyards  are  so  situated  that  they  can  be  submerged 
with  water  for  a  period  of  at  least  forty  days  during  winter,  the 
insect  can  be  drowned.  But  this  method  is  obviously  of  limited 
application. 

It  is  found  that  vines  growing  in  very  sandy  soil  resist  the  attacks 
of  the  Grape  Phylloxera.  This  is  supposed  to  be  due  to  the  diffi- 
culty experienced  by  the  insect  in  finding  passages  through  such 
soil. 

The  method  of  destroying  the  pest  which  is  most  generally  avail- 
able is  by  the  use  of  carbon  bisulphide.  See  Chapter  XIV. 

Sub-Family  III.  —  PEMPHIGIN^E.* 

The  Pemphigince  includes  those  genera  of  plant-lice  in  which  the 
front  wings  have  three  discoidal  veins,  and  of  which  the  third  dis- 
coidal  vein  has  only  one  fork  or  is  simple  ;  the  honey-tubes  are 
tuberculiform  or  wanting. 

In  habits  and  transformations  it  is  an  unusually  interesting  group. 
As  a  rule  the  species  live  above  ground,  although  with  some  there 
are  root-inhabiting  forms.  Many  species  are  remarkable  for  the 
form  and  abundance  of  their  excretions  ;  others  cause  abnormal 
vegetable  growths  or  galls  within  which  they  live.  The  galls  made 
by  the  different  species  vary  greatly  in  form  ;  but  each  species  pro- 
duces a  characteristic  gall. 

The  species  chosen  to  illustrate  this  sub-family  represent  two 
sections  of  it,  as  indicated  below  : 

Section  I.—  PEMPHIGINI. 

This  section  includes  genera  in  which  the  third  discoidal  vein  of 
the  front  wings  is  simple  ;  the  antennae  are  six-jointed. 


*  Pemphiglnae,  Pemphigus:  pemphix  (Ttejufiig),  a  blister. 


HEMIPTERA.  ^5 

Three  genera  occur  in  this  country.  These  can  be  distinguished 
as  follows : 

A.  Hind  wings  with  two  discoidal  veins.  i.  PEMPHIGUS. 

A  A.  Hind  wings  with  only  one  discoidal  vein. 

B.  Antennae  six-jointed.  2.  TETRANEURA 

BB.  Antennae  five-jointed.  3.  HORMAPHIS 

Among  the  common  representatives  of  this  section  are  certain 
species  of  Pemphigus,  which  make  galls  upon  various  trees  of  the 
genus  Populus.  One  of  these,  the  Poplar-leaf  Gall-louse,  Pemphi- 
gus populicaulis,  is  common  on  the  leaves  of  cotton-wood  and  of 
aspen.  It  makes  a  swelling  the  size  of  a  small  marble  on  the  leaf  at 
the  junction  of  the  petiole  with  the  blade.  This  gall  is  of  a  reddish 
tint,  and  has  on  one  side  a  slit-like  opening.  In  the  early  part  of 
the  season  each  gall  is  occupied  by  a  single,  wingless  female,  prob- 
ably the  agamic  stem-mother,  which,  by  midsummer,  becomes  the 
mother  of  numerous  progeny;  these  often  amount  to  one  hundred 
and  fifty  in  number. 

A  closely  allied  species  occurs  throughout  the  Western  and  South- 
western States,  which  makes  a  similar  gall  near  the  base  of  the  leaf 
of  Populus  monolifera  and  P.  balsamifera.  This  gall  has  a  trans- 
verse slit-like  opening,  which  probably  suggested  the  name  of  the 
insect,  Pemphigus  populi-transversus.  As  in  the  preceding  species, 
the  gall  is  started  in  the  spring  by  a  single,  wingless  stem-mother ; 
by  the  latter  part  of  June  the  stem-mother  is  surrounded  with  young 
of  various  sizes,  all  covered  with  the  usual  white  secretion,  and 
jnixed  with  liquid  globules.  A  generation  of  winged  individuals  is 
produced  in  the  autumn,  sometimes  not  until  the  leaves  have  fallen. 

Another  of  these  species  is  known  as  the  Vagabond  Gall-louse, 
Pemphigus  vagabundus.  It  infests  the  tips  of  the  twigs  of  certain 
cotton-woods  and  the  balsam  poplar  ;  here  it  makes  large  corrugated 
galls,  which  somewhat  resemble  the  flower  of  the  double  cockscomb 
of  our  gardens.  These  galls  turn  black,  and  remain  on  the  trees 
during  the  winter.  On  opening  the  galls  in  midwinter  I  have  found 
many  remains  of  winged  lice  in  them. 

Section  II.— SCHIZONEURINI. 

This  section  includes  genera  in  which  the  third  discoidal  vein  of 
the  front  wings  is  forked  ;  the  antennae  are  six-jointed.  Two  genera 


1 66  AN  INTRODUCTION    TO  ENTOMOLOGY. 

occur  in  this  country,  Colopha  and  Schizoneura.     In  Coloplia  the  hind 
wings  have  only  one  discoidal  vein  ;  in  Schizoneura  they  have  two. 

The  Cockscomb  Elm  Gall,  Colopha  ulmicola. — Among  the  gall- 
making  species  of  this  section  this  is  probably  the  most  familiar  one. 
The  gall  is  an  excrescence  or  follicle  like  a  cock's  comb,  which  rises 
abruptly  from  the  upper  surface  of  the  leaves  of  elm  ;  it  is  usually 
about  an  inch  long  and  a  quarter  of  an  inch  high ;  it  is  compressed, 
and  has  its  sides  wrinkled  perpendicularly  and  its  summit  irregularly 
gashed  and  toothed  ;  it  is  of  a  paler  green  color  than  the  leaf  and 
more  or  less  red  on  the  side  exposed  to  the  sun ;  it  opens  on  the 
under  side  of  the  leaf  by  along  slit-like  orifice  ;  inside,  it  is  wrinkled 
perpendicularly  into  deep  plaits.  The  complete  life-history  of  this 
species  is  not  known.  According  to  Riley  and  Monell  there  is  a 
winter  egg,  which  is  usually  inclosed  in  the  dry  skin  of  a  sexual 
female.  This  can  be  found  during  winter  in  the  crevices  of  the  bai'k 
of  the  White  Elm.  The  stem-mother  which  hatches  from  this  egg 
forms  the  gall.  She  gives  birth  to  numerous  offspring ;  these 
become  winged,  and  constitute  the  only  generation  produced  within 
the  gall.  These  winged,  agamic  females  issue  from  the  slit-like 
opening  of  the  gall  ;  and  each  gives  birth  in  the  course  of  a  day  or 
so  to  upwards  of  a  dozen  young.  These  are  born  as  pseudova. 
They  have  well  developed  mouth-parts;  and  it  is  probable  that 
when  fully  grown  they  give  birth  to  the  sexual  generation. 

To  the  genus  Schizoneura  belong  several  of  our  most  conspicuous 
'Woolly  Aphids."  Among  them  are  the  following: 

The  Alder  Blight,  Schizoneura  tesselldta. — This  woolly  louse  is 
often  found  crowded  together  on  the  under  side  of  the  branches  of 
alder  (Alnusrubra\  and  concealed  beneath  a  covering  of  downy  ex- 
cretion. It  also  excretes  abundantly  honey-dew.  The  result  is 
that  the  branches  infested  by  this  insect,  and  those  beneath  the 
cluster  of  Aphids,  become  blackened  with  fungi  that  grow  upon 
this  secretion.  There  is  also  a  curious  fungus  which  grows  in  large 
spongy  masses  immediately  beneath  the  cluster  of  plant-lice ;  this  is 
known  to  botanists  as  Scorias  spongiosum.  It  is  evidently  fed  by 
the  honey-dew  that  falls  upon  ft. 

The  Beech-tree  Blight,  Schizoneura  imbricdtor. — This  infests  both 
the  twigs  and  leaves  of  beech.  Like  the  preceding  species  it  oc- 
curs in  clusters  of  individuals,  each  of  which  is  clothed  with  a  con- 
spicuous downy  excretion.  These  clusters  often  attract  attention 
by  the  curious  habit  which  the  insects  have  of  waving  their  bodies  up 
and  down,  the  plume-like  masses  of  excretion  rendering  them  very 


HEMIPTERA.  1 67 

conspicuous.  When  an  infested  limb  is  jarred,  the  Aphids  emit  a 
shower  of  honey-dew.  Owing  to  the  abundance  of  this  secretion, 
the  branches  and  leaves  of  an  infested  tree  become  blackened  by 
growths  of  fungi,  as  with  the  preceding  species. 

The  Woolly-louse  of  the  apple,  Schizoneura  lamgera.—lht 
Woolly-louse  of  the  apple  is  one  of  the  best  known  pests  of  the 
fruit-grower.  In  its  most  conspicuous  form  it  appears  on  the  trunk 
and  limbs  of  apple-trees.  It  congregates  in  clusters  of  individuals, 
which  are  conspicuous  on  account  of  the  woolly  excretion  with  which 
their  bodies  are  clothed.  They  are  especially  injurious  to  young 
trees,  the  bark  of  which  becomes  deeply  pitted  and  scarred  by  their 
attacks.  The  bark  apparently  ceases  to  grow  at  the  point  of  attack, 
but  swells  into  a  large  ridge  about  the  cluster  of  lice,  leaving  them 
in  a  sheltered  pit.  The  lice  also  frequently  congregate  in  the  axils 
of  the  leaves  and  the  forks  of  the  branches.  This  species  resembles 
the  grape  Phylloxera  in  having  a  root-inhabiting  form,  which  causes 
knotty  swellings  on  the  fibrous  roots.  It  is  the  presence  of  this  form 
which  makes  this  pest  such  a  difficult  one  to  combat. 

Although  this  insect  has  been  known  since  the  close  of  the  last 
century,  its  complete  life-history  has  not  been  traced  out.  As  with 
all  the  Pemphiginae  the  transformations  of -which  we  know,  and  with 
Phylloxera,  there  is  in  this  species  a  generation  of  mouthless,  wing- 
less, and  generally  degraded  sexual  individuals.  The  females  of  this 
generation  produce  each  a  winter  egg.  This  can  be  found  in  the 
winter  in  the  crevices  of  the  bark,  and  in  the  pits  caused  by  the 
trunk  form.  It  is  frequently  enveloped  in  the  dry  skin  of  the  sexual 
female.  The  trunk  type  at  least  of  the  wingless,  agamic  form  gives 
birth  to  living  young  not  enveloped  in  a  pellicle.  As  the  season 
advances  there  appears  a  generation  of  winged  individuals.  These 
are  probably  agamic  ;  but  whether  they  produce  the  sexual  genera- 
tion directly  or  whether  there  intervenes  one  or  more  agamic  genera- 
tions has  not  been  determined.  At  Washington  I  have  seen  both 
the  root  and  trunk  type  of  the  wingless,  agamic  form  maintain  them- 
selves throughout  an  entire  winter  without  the  intervention  of  a 
winter  egg.  I  presume  this  is  a  common  occurrence  farther  south. 

As  one  form  of  this  insect  works  deep  in  the  ground  upon  the 
fibrous  roots  of  the  trees,  the  same  difficulties  are  met  in  attempting 
to  destroy  it  that  are  presented  by  the  grape  Phylloxera.  In  fact, 
except  in  case  of  an  especially  valuable  tree,  I  do  not  believe  that  it 
will  pay  to  attempt  to  save  a  tree  that  has  become  badly  infested  by 
the  woolly  aphis.  It  will  be  cheaper  to  dig  the  tree  up  and  burn  it, 


1  68  AN  INTRODUCTION   TO  ENTOMOLOGY. 

and  devote  the  ground  to  some  other  use.  Some  other  species  of 
tree  can  be  safely  planted  in  the  same  place,  but  not  an  apple. 
Great  care  should  be  taken  in  putting  out  trees  from  a  nursery  to  see 
that  they  are  free  from  this  pest.  If  there  is  any  doubt,  the  trees 
should  be  washed,  roots  and  all,  in  a  strong  solution  of  soap.  It  is 
well  also  to  put  in  the  fork  of  the  trees  a  piece  of  hard  soap,  which 
will  be  dissolved  and  washed  down  by  the  rains.  This  will  serve  to 
prevent  certain  other  pests  as  well  as  the  woolly  aphis  from  getting 
a  foothold.  In  case  it  is  desired  to  rid  an  infested  tree  of  this  pest, 
the  trunk  form  should  be  washed  off  with  a  strong  solution  of  soap 
applied  with  a  sponge,  taking  care  to  destroy  all  eggs  ;  and  the 
ground  should  be  treated  with  carbon  bisulphide,  as  for  the  grape 
Phylloxera. 


Sub-Family  IV.  — 

The  sub-family  Aphidinae  includes  those  genera  in  which  the  third 
discoidal  vein  of  the  front  wings  is  twice  forked  ;  the  hind  wings  have 
two  discoidal  veins  ;  and  the  honey-tubes  are  usually  well'  developed, 
sometimes  tuberculiform  or  obsolete.  The  number  of  species  belong- 
ing to  this  group  is  very  great  ;  it  being  the  largest  of  the  sub-families 
of  the  Aphididae.  Most  of  the  species  live  above  ground,  on  the 
surface  of  leaves  or  twigs  of  woody  plants  or  upon  the  leaves 
and  stems  of  the  more  succulent  species.  I  do  not  know  of  any 
species  that  produce  galls. 

Ldchnus.  —  The  largest  of  our  species  of  Aphididae  belong  to  the 
genus  Lachnus.  L.  cdryce  is  found  on  the  pig-nut 
hickory,  clustered  on  the  under  side  of  the  limbs 
in  summer;  it  is  interesting  from  being  perhaps 
our  largest  plant-louse,  measuring  to  the  tip  of  the 
FIG.  i38.—  Lachnus.  abdomen  6  mm.  (0.24  inch),  and  more  than  10  mm. 

(0.4  inch)  to  the  tip  of  the  wings. 

Aphis.  —  To  the  genus  Aphis,  in  its  restricted  sense,  belong  a  con- 
siderable number  of  the  important  species  of  this  sub-family.  The 
species  that  occurs  in  such  immense  numbers  on  cabbage  is  Aphis 
brassicce.  It  is  the  mpst  common,  and,  perhaps,  the  most  injurious 
species  that  occurs  in  the  vegetable  gardens  of  this  country.  The 
Corn  Plant-louse  is  Aphis  maidis.  This  species,  according  to  the 
observations  of  Forbes,  winters  in  the  wingless,  agamic  form  in  the 
earth  of  fields  previously  infested.  In  the  spring  it  appears  to  be 
strictly  dependent  upon  a  species  of  ant,  Lasius  alienus,  which  mines 
along  the  principal  roots  of  the  corn,  collects  the  plant-lice,  and 


HEMIPTERA.  169 

conveys  them  into  these  burrows,  and  there  watches  and  protects 
them.  In  a  short  time  after  the  lice  have  been  transferred  to  the 
roots  of  the  corn,  they  mature  a  winged  generation,  by  means  of 
which  adjacent  fields  may  be  stocked.  These  facts  indicate  the 
inadvisability  of  planting  corn  on  a  field  that  was  infested  by  this 
insect  the  previous  year.  The  species  of  Aphis  that  has  attracted 
the  most  attention  recently  is  Aphis  mdli.  This  has  occurred  in  im- 
mense numbers  on  the  young  leaves  of  apple.  Usually  the  injuries 
of  this  species  are  confined  to  the  terminal  shoots  of  a  few  branches ; 
but  in  seasons  favorable  to  its  development,  the  entire  tree  becomes 
infested.  It  is  necessary  then  to  resort  to  the  use  of  alkaline  washes. 
(See  Chapter  XIV.) 

Myzus. — Two  species  of  Myzus  are  very  common.  One  of  these, 
the  Cherry-tree  Aphis,  Myzus  cerasi,  infests  the  leaves  and  twigs  of 
cherry.  Sometimes  it  becomes  so  abundant  that  it  completely  covers 
the  infested  tree.  The  other  species  referred  to  is  the  Peach-tree 
Aphis,  Myzus  per sicce.  This  lives  on  the  under  side  of  the  leaves, 
causing  them  to  thicken  and  curl.  Its  injuries  are  usually  confined 
to  the  terminal  portion  of  a  few  branches.  The  easiest  way  to 
destroy  this  pest  is  to  dip  the  infested  branches  into  a  pail  of  soap 
solution.  There  is  a  serious  disease  of  the  peach  which  causes  the 
leaves  to  curl  in  a  similar  manner,  and  which  is  known  as  the  curl- 
leaf.  This  disease  can  be  distinguished  from  the  injuries  of  the 
Peach-tree  Aphis  by  the  absence  of  plant-lice  in  the  curled  leaves. 
It  is  caused  by  a  fungus  known  as  Exoascus  deformans. 

The  Hop  Aphis,  Phorodon  Mmuti.—This  species  often  swarms  in 
hop-yards  to  such  an  extent  that  it  seriously  injures  the  crop.  An 
interesting  and  important  feature  in  its  life-history  is  that  it  passes 
the  winter  on  plum-trees.  As  soon  as  the  leaves  of  plum  appear  in 
the  spring,  the  first  generation  of  this  Aphid  hatches  from  the  winter 
eggs  on  plum.  The  first  and  second  generations  are  wingless,  agamic 
females,  which  live  upon  the  plum;  the  third  appears  early  in  June, 
is  winged,  and  migrates  to  the  hops.  From  this  generation  there 
descend  several  generations  of  wingless,  agamic  females.  Of  these 
there  may  be,  according  to  Riley's  observations,  upon  which  this 
account  is  based,  as  many  as  eight,  making  the  last  one  the  eleventh 
of  the  season.  Late  in  August  and  early  in  September  the  offspring 
of  the  eleventh  generation  and  of  the  members  of  the  other  genera- 
tions that  are  still  alive  become  winged.  These  winged  individuals 
are  agamic  females  which  migrate  to  plum-trees  and  there  produce 
wingless,  sexual  females.  Late  in  September,  there  is  produced  on 


I7O  AN  INTRODUCTION    TO   ENTOMOLOGY. 

the  hops  by  some  members  of  the  eleventh  agamic  generation  a 
generation  of  winged  males.  These  fly  to  the  plum-trees  and  mate 
with  the  wingless  sexual  females,  which  are  already  there.  Soon 
after  this  the  eggs  are  deposited  on  the  smaller  twigs  and  branches 
of  the  plum,  in  and  around  the  angles  formed  by  the  buds  and  twigs. 
Each  female  lays  from  one  to  three  eggs. 

If  it  should  be  proven  that  this  species  can  winter  only  on  plum, 
the  separation  of  plum  and  hop  culture  would  be  advisable.  But 
further  observations  are  needed  before  we  are  warranted  in  advising 
the  destruction  of  plum-trees  in  the  hop-growing  sections.  But  we 
can  urge  the  careful  destruction  of  all  Aphids  on  plum-trees  early  in 
the  season.  The  most  practicable  way  of  doing  this  is  by  spraying 
with  a  strong  solution  of  soap  or  with  kerosene  emulsion.  (See 
Chapter  XIV.) 


Family  V.  — 

(Jumping  Plant-lice^) 

The  Jumping  Plant-lice  are  comparatively  small  insects;  our 
more  common  species  measure  only  3  or  4  millimeters  in 
length  ;  and  our  largest  species,  the  giant,  comparatively  speak- 
ing, measures  only  6  mm.  and  has  a  wing-expanse  of  12  mm. 
They  resemble  somewhat  the  winged  Aphids  in  appearance  ;  but 
they  look  more  like  miniature  Cicades  (Fig.  139). 
They  are,  however,  closely  allied  to  the  Aphids  ;  but 
they  differ  from  them  in  the  firmer  texture  of  the 
body,  in  the  stouter  limbs,  in  having  the  hind  legs 
fitted  for  jumping,  and  in  the  9-  or  lo-jointed  an- 
tennae. The  antennae  are  peculiar  also  in  being 
armed  at  the  tip  with  two  bristles,  or  less  commonly 
with  one.  "  The  rostrum  is  short,  three-jointed,  and 
placed  almost  between  the  fore  coxae,  where  it  fits  into 
a  grooved  space.  Both  sexes  are  always  winged  in  the  adult  ;  the 
wing-covers  are  ample,  and,  while  often  transparent,  are  much  thicker 
than  the  wings,  and  furnished  with  stout  curving  veins,  which 
enclose  a  few  areoles  at  the  tip."  (Uhler.) 

The  Psyllidae  subsist  entirely  upon  the  juices  of  plants;  many 
species  form  galls.  But  it  is  rare  that  any  of  them  appear  upon  culti- 
vated plants  in  sufficient  numbers  to  attract  attention,  except  in  case 
of  the  Pear-tree  Psylla. 

*  Psyllidae,  Psylla  :  psylla  tyvXha),  a  flea. 


HEMIPTERA.  i;i 

The  Pear-tree  ?sy\\z,Psylla  pyri—  This  is  a  minute  species  which 
measures  only  2.5  mm.  (o.i  inch)  to  the  tip  of  the  folded  wings.  It 
invests  the  smaller  limbs  and  twigs  of  pear-trees,  causing  them  to 
droop  and  fall  off.  It  can  be  destroyed  in  the  same  way  as  recom- 
mended for  plant-lice  in  the  same  situation. 

Family  VI. — MEMBRACID^E.* 
(  Tree-hoppers.) 

We  have  many  common  representatives  of  this  sub-family ;  and 
the  grotesque  forms  of  certain  species  are  sure  to  attract  the  attention 
of  collectors.  The  general  outline  of  the  body  is  usually  triquetral, 
that  is,  shaped  like  a  beech-nut.  But  many  of  the  species  have  one 
or  more  of  the  angles  prolonged,  or  are  furnished  with  prominent 
humps  or  tubercles.''  The  most  useful  character  for  distinguishing 
members  of  this. family  is  the  prolongation  of  the  prothorax  back- 
ward above  the  abdomen.  Sometimes  it  extends  back  to  the  tip  of 
the  abdomen,  and  completely  covers  the  wings.  This  development 
of  the  prothorax  reminds  us  of  what  occurs  in  the  Tettiginae,  of  the 
order  Orthoptera. 

Many  species  of  the  Membracidae  live  upon  bushes  or  small  trees  ; 
and  all  are  good  leapers.  Hence  the  common  name,  Tree-hoppers. 
Although  these  insects  subsist  upon  the  juices  of  plants,  I  have  never 
known  them  to  occur  in  sufficient  numbers  to  be  of  economic  impor- 
tance. Some  members  of  this  family  excrete  honey-dew,  and  are  at- 
tended by  ants,  as  are  the  Aphids.  The  transformations  of  but  few 
species  have  been  observed.  Some  of  these  make  slits  in  twigs,  in 
which  they  lay  their  eggs.  The  immature  forms  of  certain  species  oc- 
cur upon  plants  in  company  with  the  adults.  But  the  early  stages 
of  the  great  majority  of  species  are  unknown  to  us. 

The  genus  Darnis  will  serve  as  a  good  illustration  of  one  of  the 
principal  types  of  this  family.  Here  the  prothorax  is  nearly 

¥all  that  can  be  seen  of  the  body  from  above.  It  is  very  convex 
in  front,  overshadowing  the  short,  transverse,  band-like  head, 
and  tapers  to  a  sharp  point,  which  extends  beyond  the  tip 
FIG.  140.      of  the  abdomen.     (Fig.  140.) 

The  Buffalo  Tree-hoppers,  Ceresa  bubalns,  represents 
another  type  belonging  to  this  family.  The  popular  name  refers  to 
the  lateral  prolongations  of  the  prothorax,  which  suggest  the  horns 


*  Membracidee,  Membracis  :  membrax  (neuppafy,  a  kind  of  Cicada. 


AN  INTRODUCTION   TO  ENTOMOLOGY. 

of  a  buffalo  (Fig.  141).     This  insect  lives  on  the  sap  of  apple,  pear, 

and  other  trees.    It  is  of  a  yellowish-green  color.  The  eggs  are  laid  in 

little  slits  in  the  bark  ;  they  hatch  in  the  spring  ;  and  the 

young  are  very  different  from  the  adult,  being  furnished 

fwith  a  pair  of  large  spines  upon  each  segment. 
The   Two-horned   Tree-hoppers,  Ceresa  diceros,  is  also 
a  common  species.     It  resembles  the  Buffalo  Tree-hopper 
FIG  i4i  -ce-     m  s^ze  anc*  form.     It  is  a  pale,  dirty  yellow,  spotted  with 
resa  buba-     brown  •    the   lateral  and  caudal    aspect  of   each   horn    is 
brown  ;  the  caudal  tip  of  the  prothorax,  and  a  large  spot 
midway  between  the  tip  and  horns  are  also  brown.     The  insect  is 
densely  clothed  with  hairs. 

The  genus  Enchendpa  illustrates  another  strange  form  found  in 
this  family.     The  Two-marked  Tree-hopper,  Enchenopa  binotdta,  (Fig. 
142,)  abounds  on  various  trees,  shrubs,  and  herbaceous 
plants.     It  is  gregarious;  and  both  adult   and   immature 
forms  are  found  clustered  together.     It  is  almost  always 
attended  by  ants.    It  lays  its  eggs  in  frothy  masses,  which  FIG      _En 
are  very  v/hite,  and  appear  like  wax.     These  egg-masses     jjjjjf"  bi*~ 
have  been  mistaken  for  insects  of    the  genus  Orthezia. 
Another  very  common  species  is  E.  curvdta.     It  is  brownish,  un- 
spotted, and  has  a  rather  longer  horn  than  the  preceding  species. 

"  To  the   genus   Telamona  (Fig.   143)  belong  our 
indigenous     humpback    forms,    of    gray,    claret,    or 
greenish    colors,  which   live   in  June  and  July  upon 
oaks,  hickories,  and  other  forest   trees.      They  gen- 
I4T'      "  erally  rest  singly  on  the  limbs  and  branches  of  the 
trees,  with  the  head  directed  away  from  the  trunk  ; 
but  in  the  younger  stages  they  keep  together   in    small   groups." 
(Uhler.) 


Family  VII.— 

(Cicadas.) 

The  large  size  and  the  well-known  songs  of  the  more  common 
species  of  this  family  render  them  familiar  objects.  It  is  only 
necessary  to  refer  to  the  Periodical  Cicada  (or  the  1  7-year  locust,  as 

*  Cicadidae,  Cicada:  Cicada,  Latin  name  of  these  insects. 


HEMIPTERA. 


'73 


it  has  been  improperly  termed)  and  to  the  Dog-day  Harvest-fly 
(Fig.  144)  to  give  an  idea  of  the  more  striking  characters  of  this 
family. 

The  species  are  generally  of  large  size,  with  a  subconical  body. 
The  head  is  wide  and  blunt,  with  prominent 
eyes  on  the  outer  angles,  and  three  bead-like 
ocelli  arranged  in  a  triangle  on  the  vertex. 
"  The  mesothorax  is  the  largest  segment,  and 
the  metathorax  is  reduced  to  a  narrow  scale. 
A  very  conspicuous  feature  in  all  of  them  is  a 
cross-like  prominence  on  the  hind  end  of  the 
former,  which  adds  great  firmness  to  this  im- 
portant part  of  the  chest.  The  wing-covers 
are  nearly  elliptical,  longer  than  the  body, 
parchment-like,  but  generally  transparent,  and 
with  a  series  of  eight  areoles  at  the  tip  ;  but  the 
hind  wings  are  more  membranous,  scarcely  ex- 
ceeding half  the  length  of  the  former,  and  with  FlG-  w.— cicada 
an  apical  series  of  six  areoles.  Their  legs  are  short  and  stout,  not 
fitted  for  leaping,  the  fore-thighs  quite  thick,  armed  with  two  or 
more  thick  teeth ;  also,  the  hind  shanks  are  bristly,  and  have  a  series 
of  sharp  spines  on  each  side. 

*"But  the  most  distinctive  peculiarity,  which  has  no  parallel  in 
any  of  the  other  groups,  appears  in  the  organs  of  sound  (of  the 
males).  These  consist  of  two  large  parchment  sacs,  ribbed  and 
gathered  into  numerous  plaits,  furnished  with  powerful  muscles,  and 
situated  in  large  cavities  at  the  base  of  the  abdomen.  When  in 
action,  the  air  is  driven  in  great  force  against  the  ribbed  surfaces,  and 
vibrations  are  set  up  which  produce  the  sound  in  accordance  with 
the  number  and  form  of  the  fluted  spaces  and  ribs."  (Uhler.) 

The  Dog-day  Harvest-fly,  or  Lyerman,  Cicada  tiblcen. — The 
shrill  cry  of  this  species,  which  is  the  most  prominent  of  the  various 
insect  sounds  heard  during  the  latter  part  of  the  summer,  has 
brought  its  author  into  prominent  notice.  This  insect  varies  both 
in  size  and  colors.  It  commonly  measures  50  mm.  (2  inches)  to  the 
tip  of  the"  closed  wings ;  it  is  black  and  green,  and  more  or  less 
powdered  with  white  beneath.  The  transformations  of  this  insect 
are  similar  to  those  of  the  following  species,  except  that  it  requires 
only  two  years  for  its  development.  It  differs  also  in  seldom,  if  ever, 
occurring  in  sufficient  numbers  to  be  of  economic  importance ;  but  a 


12 


174  AN  INTRODUCTION   TO  ENTOMOLOGY. 

brood  of  it  appears  each  year.  It  is  distributed  from  New  York  to 
Rio  de  Janeiro. 

The  Periodical  Cicada,  Cicada  septendecim. — This  species  is  now 
commonly  known  as  the  i/-year  locust.  But  the  term  locust,  as  ap- 
plied to  it,  is  a  misnomer,  the  locusts  being  Orthopterous  insects. 
I  therefore  adopt  the  more  appropriate  name,  Periodical  Cicada, 
which  has  been  proposed  for  it.  This  species  is  remarkable  for  the 
long  time  required  for  it  to  attain  its  maturity.  The  eggs  are  laid 
in  the  twigs  of  various  trees  ;  the  female  makes  a  series  of  slits  in 
the  twig,  into  which  the  eggs  are  placed.  Sometimes  this  Cicada 
occurs  in  such  great  numbers  that  they  seriously  injure  small  fruit- 
trees,  by  ovipositing  in  the  twigs  and  smaller  branches.  The  larvae 
hatch  in  about  six  weeks.  They  soon  voluntarily  drop  to  the 
ground,  where  they  bury  themselves.  Here  they  obtain  nourish- 
ment by  sucking  the  juices  from  the  roots  of  forest  and  fruit  trees. 
And  here  they  remain  till  the  seventeenth  year  following.  They 
emerge  from  the  ground  during  the  last  half  of  May,  at.  which  time 
the  empty  pupa-skins  may  be  found  in  great  numbers,  clinging  to 
the  bark  of  trees  and  other  objects.  The  insects  soon  pair,  the 
females  oviposit,  and  all  disappear  in  a  few  weeks. 

More  than  twenty  distinct  broods  of  this  species  have  been  traced 
out ;  so  that  one  or  more  broods  appear  somewhere  in  the  United 
States  nearly  every  year.  In  many  localities,  several  broods  coexist ; 
in  some  cases  there  are  as  many  as  seven  distinct  broods  in  the  same 
place,  each  brood  appearing  in  distinct  years.  There  is  a  variety  of 
the  species  in  which  the  period  of  development  is  only  thirteen  years. 
This  variety  is  chiefly  a  Southern  form,  while  the  seventeen-year 
broods  occur  in  the  North. 


Family  VIII.— FULGORID.E.* 

(Lantern-flies  et  al.] 

This  family  is  remarkable  for  certain  exotic  forms  which  it  con- 
tains. Chief  among  these  is  the  great  Lantern-fly  of  Brazil,  which  is 
figured  in  many  popular  works  on  insects.  Scarcely  less  strange  are 
the  Candle-flies  of  China  and  the  East  Indies.  There  does  not  seem 

*  Fulg6ridae,  FulgOra :  fulgor,  flashing  lightning. 


HEMIPTERA.  175 

to  be  any  typical  form  of  the  body,  characteristic  of  this  family.  The 
different  genera  differ  so  greatly  that,  on  superficial  examination,  they 
appear  to  have  very  little  in  common.  Some  even  resemble  butter- 
flies and  moths,  while  others  might  easily  be  mistaken  for  certain 
Neuropterous  genera. 

The  most  useful  character  for  recognizing  these  insects  is  the 
form  and  position  of  the  antennae.  These  are  bristle-shaped,  and 
inserted  into  a  button-shaped  base  on  the  sides  of  the  cheeks  beneath 
the  eyes.  Although  the  Fulgoridae  are  vegetable-feeders,  none  of 
our  species  have  attracted  the  attention  of  agriculturists.  There 
are,  however,  certain  exotic  species  which  do  great  injury  to 
crops. 

The  Brazilian  Lantern-fly,  Latcrndria  phosphorea. — This  is  the 
largest  species  of  the  family,  and  is  one  of  the  most  striking  in  ap- 
pearance of  all  insects.  It  has  immense  wings,  expanding  nearly 
150  mm.  (6  inches).  Upon  each  hind  wing  there  is  a  large  eye-like 
spot.  But  the  character  which  makes  this  insect  especially  promi- 
nent is  the  form  of  the  head.  There  is  a  great  bladder-like  prolonga- 
tion extending  forwards.  This  prolongation  has  been  aptly  com- 
pared to  the  pod  of  a  peanut.  In  a  specimen  before  me,  the  body, 
exclusive  of  the  head,  measures  45  mm.  (1.8  inches)  in  length  ;  while 
the  head  alone  measures  30  mm.  (1.2  inches).  The  specific  name 
refers  to  the  supposed  luminosity  of  this  part.  Prof.  Branner  tells 
us  of  various  superstitions  held  by  the  Brazilians  regarding  this 
insect.  For  example  :  "  Xh^at  it  has  great  powers  of  flight,  and  when 
in  its  wild  career  it  strikes  any  living  object — if  an  animal,  no  matter 
how  large  or  powerful — it  falls  dead  upon  the  spot ;  if  a  tree,  it  soon 
wilts  and  dies." 

The  Chinese  Candle-fly,  Fulgoria  candeldria. — This  is  another 
very  prominent  insect,  and  also  one  that  has  the  reputation  of  being 
phosphorescent.  It  is  commonly  represented  in  collections  of 
exotic  insects,  and  it  is  often  figured  by  the  Chinese.  It  is  smaller 
than  the  preceding  species,  measuring  about  two  thirds  as  much  in 
length.  The  prolongation  of  the  head  is  proportionately  longer 
than  in  the  Brazilian  insect ;  but  it  is  more  slender,  and  is  conical. 
The  color  of  the  insect  is  greenish  or  orange-yellow,  with  banded 
wing-covers. 

The  following  of  our  native  genera  will  serve  to  illustrate  some 
of  the  variations  in  form  represented  in  this  country.  Our  species 
are  all  small  compared  with  the  exotics  described  above. 


1/6  AN  INTRODUCTION   TO  ENTOMOLOGY. 

Scolops.  —  In  this  genus  the  head  is  greatly  prolonged  (Fig.  145), 
as  with   the  exotic  Candle-flies.     Our  more  common  species,  how- 
ever,   measure   only  about  8   mm.  (0.31   inch)  in 
length. 

Otiocerus.  —  In  this  genus,  the  body  is  oblong; 
the  head  is  compressed,  with  a  double  edge  both 
above  and  below,  and  the  antennae  are  furnished 
with  tape-like  appendages.  "  Otiocerus  coquebertiiis 
a  gay  lemon-yellow  or  cream-colored  species,  with  a  broad  stripe  on 
the  side  of  the  face  and  wavy  red  forked  lines  on  the  wing-covers  ; 
the  head,  as  seen  from  the  side,  is  of  the  form  of  a  ploughshare,  with 
little  brown  eyes  standing  out  like  beads.  The  antennae  have  three 
bent  appendages  resembling  strips  of  tape.  It  measures  about 
8  mm.  (0.3  inch)  to  the  tip  of  wing-covers,  lives  upon  the  leaves  of 
grape-vines,  oaks,  and  hickory,  in  July,  August,  and  September." 
(Uhler.)  It  is  distributed  over  the  entire  Eastern  United  States. 

Ormenis.  —  In  our  common  representatives 
of  this  genus  the  wing-covers  are  broad,  and 
closely  applied  to  each  other  in  a  vertical 
position  ;  they  are  more  or  less  truncate,  and 
give  the  insect  a  wedge-shape  outline.  O.  sep- 
tentriondlis  (Fig.  146)  is  a  beautiful  pale-green 

.  ,  i-.ii          i    «A.  1    •    i      r         i  FIG.  146.  —  Ormenis  septen- 

species  powdered  with  white,  which  feeds  on  trionaiis. 

wild  grape-vines,  drawing  nourishment   from 

the   tender    shoots   and    mid-ribs  of    the  leaves,  during   its   young 

stages. 

Family  IX.—  CERCOPIM:.* 
(Spittle-insects  or  Frog-hoppers^) 

This  and  the  following  family  agree  with  the  Membracidae  in  h?v- 
ing  the  antennae  inserted  in  front  of  and  between  the  eyes.  But  the 
Cercopidae  differs  from  the  Membracidae  in  lacking  the  backward  pro- 
longation of  the  prothorax,  and  from  the  Jassidae  in  the  character  of 
the  spines  upon  the  hind  tibiae.  Here  we  find  the  tibiae  armed  with 
one  or  two  stout  teeth,  and  the  tip  crowned  with  short,  stout  spines. 
The  Cercopidae  "mark  an  important  advance  in  the  direction  of  the 
Heteroptera  by  the  large  size  of  the  prothorax  and  increased  freedom 
of  the  fore  legs.  This  extensive  piece  is  no  longer  a  mere  cap  or 


*  CercSpidae,  Cercopis  :  Cercops  (KepKaoifr),  one  of  a  fabled  race  of  men 


HEM1PTERA.  177 

scale  as  in  most  of  the  Fulgoridae,  nor  yet  a  lid,  case,  or  bubble-like 
expansion  as  in  the  Membracidae,  but  is  an  important  regional  por- 
tion, exercising  various  important  functions."  (Uhler.) 

Our  most  common  representatives  of  the  family  are  the  insects 
known  as  spittle-insects  or  frog-hoppers.  During  the  summer  months 
one  often  finds  upon  various  shrubs  and  herbs  masses  of  white  froth. 
In  the  midst  of  each  of  these  masses  there  lives  a  young  insect,  a 
member  of  this  family.  In  some  cases  as  many  as  four  or  five  insects 
inhabit  the  same  mass  of  foam.  The  froth  is  supposed  to  consist  of 
sap,  which  the  insect  has  pumped  from  the  plant,  by  means  of  its 
rostrum,  and  passed  through  its  alimentary  canal.  It  is  asserted 
that  these  insects  undergo  all  their  transformations  within  this  mass; 
that  when  one  is  about  to  moult  for  the  last  time,  a  clear  space  is 
formed  about  its  body;  the  superficial  part  of  the  foam  dries,  so  as 
to  form  a  vaulted  roof  to  a  closed  chamber  within  which  the  change 
of  skin  is  made.  The  adult  insects  wander  about  on  herbage 
and  trees.  They  have  the  power  of  leaping  well.  The  name  frog- 
hoppers  has  doubtless  grown  out  of  the  fact  that  formerly  the  froth 
was  called  "  frog-spittle,"  and  was  supposed  to  have  been  voided  by 
the  tree-frogs  from  their  mouths.  The  name  is  not,  however,  inap- 
propriate ;  for  the  broad  and  depressed  form  of  our  more  common 
species  is  something  like  that  of  a  frog. 

Our  more  common  species  of  spittle-insects  belong  to  the  genus 
Aphrophora.  They  are  mostly  brownish  insects,  and  are  variously 
banded  and  spotted.  One  of  the  common  species  of  the  Eastern 
United  States  is  Aphrophora  quadrangular  is  (Fig.  147).  The  adult 
of  this  species  is  a  brownish  insect,  densely  covered 
with  microscopic  hairs,  and  black  beneath ;  the  wing- 
covers  are  marked  with  two  oblique,  brown  bands, 
which  are  confluent  near  the  middle  of  the  costal  mar- 
gin ;  the  humeral  region  is  dusky ;  and  the  tip  of  FlG.  yj.-^j 
each  wing-cover  is  marked  with  a  small  blackish  curve ;  ran&lar'is" 
the  ocelli  are  black,  but  indistinct.  This  species 
measures  from  6  mm.  to  8  mm.  (0.24  to  0.31  inch)  in  length. 
Somewhat  resembling  this  species,  and  also  common  in  the 
East,  is  Aphrophora  quadranotdta.  In  this  species  the  body  is 
pale ;  the  wing-covers  are  dusky,  each  with  two  large  hyaline  costal 
spots,  margined  with  dark  brown;  the  ocelli  are  blood-red ;  and  the 
head  and  pronotum  are  furnished  with  a  slightly  elevated,  median, 
longitudinal  line. 

To  the  genus  Clastoptera  belong  certain  other  common  members 


*\ 


1  78  AN  INTRODUCTION    TO   ENTOMOLOGY. 

« 

of  this  family.  In  this  genus  the  body  is  short  and  plump,  some- 
times nearly  hemispherical;  the  species  are  small,  our  common  forms 
ranging  from  3  mm.  to  6  mm.  (0.12  to  0.24  inch)  in  length.  Clastop- 
tera  proteus  is  a  conspicuous  species  on  account  of  its  bright  yellow 
markings.  It  varies  greatly  in  color  and  markings;  but  the  most 
striking  forms  are  black,  with  three  transverse  yellow  bands,  two  on 
the  head  and  one  on  the  thorax;  and  with  the  scutellum  and  a 
large  oblique  band  on  each  wing-cover  yellow.  Another  common 
species  is  Clastoptera  obtusa.  This  occurs  on  black  alder  in  summer 
and  autumn.  "  It  is  of  a  claret-brown  color  above,  marked  with  two 
pale  bands  on  the  vertex,  two  on  the  prothorax,  and  a  wavy,  broader 
band  on  the  wing-covers.  The  membrane  is  often  whitish,  the 
waved  band  is  extended  exteriorly,  and  there  is  a  pale  V-shaped 
figure  on  the  end  of  the  scutellum." 


Family  X.—  JASS 
(Leaf  -hoppers.  ) 

This  the  highest  family  of  the  Homoptera  is  a  very  extensive  one. 
And  it  is  also  of  considerable  economic  importance;  for  it  includes 
a  number  of  species  that  are  very  injurious  to  vegetation.  The  body 
is  more  slender  than  in  the  preceding  family;  with  which  this  agrees 
in  the  insertion  of  the  antennae  in  front  of  and  between  the  eyes, 
and  in  the  absence  of  a  prolongation  of  the  prothorax  above  the 
abdomen.  But  the  most  salient  character  which  distinguishes  the 
Jassidse  is  the  structure  of  the  hind  tibiae.  These  are  nearly  or 
quite  as  long  as  the  abdomen,  curved,  and  armed  with  a  row  of 
spines  on  each  margin.  The  form  of  the  body  "  is  commonly  long 
and  slender,  often  spindle-shaped,  with  a  large  transverse  prothorax 
not  much  wider  than  the  head.  The  front  is  generally  an  oblique, 
cross-ribbed,  inflated  prominence,  with  the  cheeks  touching  the 
anterior  coxae,  but  rarely,  if  ever,  restraining  their  movement.  They 
have  a  rather  large  triangular  scutellum  ;  the  wing-covers  curve  over 
the  sides  of  the  abdomen,  appear  as  tapering  towards  the  tip,  and 
the  membrane  is  distinguished  from  the  more  leathery  corium." 
(Uhler.) 

The  Jassidse  are  able  to  leap  powerfully  ;  and,  as  they  are  more 
often  found  on  the  leaves  of  herbage  and  on  grass  than  elsewhere, 
they  have  been  termed  leaf-hoppers. 

*  Jassidae,  Jassus  :  Jassus,  a  proper  name. 


HEMIPTERA.  179 

The  family  has  been  divided  in  various  ways  by  different  writers. 
It  seems  best  to  recognize  in  this  place  only  two  sub-families ;  although 
seven  are  proposed  by  Stal.  These  two  sub-families  can  be  distin- 
guished as  follows: 

A.  Ocelli  placed  on  the  front  rim  of  the  vertex  close  to  the  eyes,  or  on  the 

front,  but  never  on  the  disk  of  the  vertex.  I.  JASSINJE. 

AA.  Ocelli  placed  upon  the  vertex.  II.  TETTIGONIN^E. 


Sub-Family  I.— 

The  more  important  members  of  the  Jassinae  from  an  economic 
standpoint  are  the  following: 

The  Destructive  Leaf-hopper,  Cicddula  exitiosa. — During  the 
winter  of  1879-80  much  damage  was  done  to  winter  grain  in  the 
Carolinas  and  Georgia  by  this  species.  It  is  a  small,  active,  brownish 
insect,  which  measures  with  its  wings  folded  about  5  mm.  (0.2  inch)  in 
length.  Its  general  form  is  well  indicated  by  the  enlarged  figure  (Fig. 
148).  It  is  very  quick,  a  good  flyer,  and  a  great  jumper. 
It  injures  grass  or  grain  by  piercing  the  midrib  of  the 
leaf  and  sucking  the  juices  from  it.  Upon  the  planta- 
tion where  I  studied  this  insect  there  was  observable  a 
most  exact  line  between  the  eaten  and  uneaten  portions  of 
the  wheat-field.  Instead  of  spreading  themselves  over 
the  field  indiscriminately,  or  half  eating  a  patch  here  and 
there,  the  leaf-hoppers  ate  the  wheat  down  to  the  ground 
as  they  progressed.  They  are  very  shy,  however,  and  fly  FlG  148  _ 
away  on  the  least  disturbance.  Judging  from  the  known  5 **{**!. 
habits  of  allied  species,  the  eggs  are  doubtless  laid  in  the  ifiThoVs 
stems  of  grasses  close  to  the  ground.  The  young  hoppers  ^^ 
when  hatched  are  almost  precisely  of  the  same  appearance 
as  the  old  ones,  except  that  they  lack  wings.  The  time  occupied  in 
attaining  full  growth  probably  does  not  exceed  a  month,  so  that 
there  are  several  broods  a  year.  These  insects  are  readily  attracted 
by  light ;  and  probably  many  of  them  could  be  destroyed  by  trap- 
lanterns,  or  by  building  bonfires  at  night.  It  is  possible,  also,  that 
many  could  be  destroyed  by  spraying  with  some  of  the  alkaline  or 
other  washes  described  in  the  chapter  on  remedies.  In  those  cases 
where  the  line  of  injury  is  a  well-marked  one,  only  a  small  part  of 
the  field  would  need  to  be  sprayed. 

The    Grape-vine    Leaf-hopper,   Erythroneura    vltis.— There    are 


180  AN  INTRODUCTION    TO   ENTOMOLOGY. 

several  species  of  Leaf-hoppers  that  infest  the  leaves  of  grape,  and 
are  known  to  grape  growers  as  the  "  Thrip."  These  all  belong  to 
the  genus  Erythroneura.  The  most  common  one  is  E.  vltis.  It  is 
a  little  more  than  3  mm.  (0.12  inch)  in  length,  crossed  by  two  blood- 
red  bands,  and  a  third  dusky  one  at  the  apex.  These  insects  pass 
the  winter  in  the  perfect  state,  hibernating  under  dead  leaves  or 
other  rubbish;  in  the  spring  they  deposit  their  eggs  on  the  young 
leaves  of  the  vine.  The  larvae  hatch  during  the  month  of  June,  and 
resemble  the  adult  insect  except  in  size  and  in  being  destitute  of 
wings.  The  insects  feed  together  on  the  under  side  of  the  leaves, 
and  are  very  quick  in  their  movements.  Like  the  preceding  species 
this  insect  can  be  destroyed  by  trap-lanterns  or  by  washes. 

The  Rose  Leaf-hopper,  Empoa  rosce. — "  Swarms  of  these  insects 
may  be  found,  in  various  stages  of  growth,  on  the  leaves  of  the  rose- 
bush, through  the  greater  part  of  the  summer,  and  even  in  winter 
upon  housed  plants.  Their  numerous  cast  skins  may  be  seen  adher- 
ing to  the  lower  sides  of  the  leaves.  They  pair  and  lay  their  eggs 
about  the  middle  of  June,  and  they  probably  live  through'the  winter 
in  the  perfect  state,  concealed  under  fallen  leaves  and  rubbish  on  the 
surface  of  the  ground."  Although  this  is  a  very  common  pest,  it 
does  not  seem  to  have  received  much  attention  from  entomologists 
since  the  time  of  Harris,  from  whom  the  above  account  is  quoted. 
It  should  be  combated  in  the  same  way  as  the  leaf-hoppers  already 
described. 

Sub-family  II. — TETTIGONIN^:.* 

The  members  of  this  sub-family  are  mostly  small  or  medium-sized 
insects,  with  long  narrow  bodies.  But  we  find  here  some  forms 
which  resemble  certain  genera  belonging  to  the  Cercopidae.  Thus 
Penthimia  includes  plump,  short-bodied  insects,  which  remind  us  of 
Clastoptera;  and  the  genus  Gypona  includes  a  large  number  of  species, 
some  of  which  resemble  very  closely  certain  species  of  Aphrophora. 
It  is,  however,  hardly  necessary  to  remind  the  student  that  a  glance 
at  the  posterior  tibiae  of  these  leaf-hoppers  will  enable  one  to  dis- 
tinguish them  from  the  Cercopids,  which  they  so  closely  resemble. 

The  genus  Diedrocephala  includes  grass-green,  or  pale-green, 
spindle-shaped  species  which  represent  better  the  typical  form  of 
this  sub-family.  The  members  of  this  genus  may  be  recognized  by 
the  long,  triangular  head  as  seen  from  above.  One  of  the  species, 

*  Tettigonlnae,  Tettigonia  :  tettix  (rernt-),  a  cicada;  gonia  (ycovia),  a  corner. 


;# 


HEMIPTERA.  !$! 

D.  fldviceps,  sometimes  greatly  injures  fields  of  grain  in  the  South. 
The  most  common  species  in  New  York  is  D.  noveboractnsis. 

The  genus  Proconia  includes  species  in  which  the  head  is  more 
blunt  than  in  the  preceding  genus,  and  is  wider  across  the  eyes 
than  the  thorax.  P.  unddta  (Fig.  149)  is  a  common  species.  "Its 
body,  head,  fore  part  of  thorax,  scutellum,  and  legs 
are  bright  yellow,  with  circular  lines  of  black  on  the 
head,  thorax,  and  scutellum.  The  underside  of  the 
abdomen  is  banded,  and  the  breast  and  legs  speckled 
with  black.  The  wing-covers  are  bluish  purple,  when 
fresh,  coated  with  whitish  powder."  (Uhler'l  It  FlG  M9.-/v<™. 

,  nia  undata. 

measures  12    mm.  (0.47  inch)  to  the  tip  of  the  wing- 
covers.     It  is  said  to  lay  its  eggs  in  single  rows  in  grape  canes ;  and 
to  puncture  with  its  beak  the  stems  of  the  bunches  of  grapes,  caus- 
ing the  stems  to  wither  and  the  bunches  to  drop  off. 

Sub-Order  III.— HETEROPTERA.* 

The  Heteroptera  includes  those  members  of  the  order  Hemip- 
tera  to  which  the  general  name  Bug  is  most  frequently  applied. 
These  insects  are  characterized,  as  already  indicated,  by  having  the 
first  pair  of  wings  thickened  at  the  base,  and  with  thinner  extremi- 
ties, which  overlap  on  the  back ;  and  by  the  position  of  the  rostrum, 
which  arises  from  the  front  part  of  the  head.  The  head  is  furnished 
with  a  more  or  less  distinct  neck,  so  that  the  cheeks  and  the  first 
pair  of  coxae  do  not  touch  each  other. 

In  this  sub-order  we  find  variations  in  structure  which  corre- 
spond closely  with  variations  in  habits.  There  are  certain  families 
the  members  of  which  are  truly  aquatic,  living  within  the  water, 
through  which  they  swim,  and  to  the  surface  of  which  they  come 
occasionally  for  air.  There  are  others  which  are  truly  terrestrial, 
living  upon  the  surface  of  plants,  or  in  other  positions  away  from 
water.  There  are  still  other  families  the  members  of  which  hold  an 
intermediate  position  between  the  aquatic  and  the  terrestrial  forms, 
living  upon  the  surface  of  water,  or  in  marshy  places. 

In  a  systematic  arrangement  of  the  Heteroptera  the  aquatic 
forms  are  placed  first  or  lowest ;  the  terrestrial  forms,  highest ; 
and  the  semiaquatic  forms  hold  an  intermediate  position. 

*  HeterSptera  :  Aeteros(eTepuS),  diverse  ;  pteron  (nrepov),  awing. 


1 82  AN  INTRODUCTION    TO  ENTOMOLOGY, 

TABLE  FOR   DETERMINING  THE   FAMILIES   OF   HETEROPTERA. 

A.  Antennae  short,  and  nearly  or  quite  concealed  beneath  the  head. 

B.  Ocelli  wanting;  insects  aquatic,  and,  excepting  Nepidse  and  Naucoridae, 
with  legs  fitted  for  swimming. 

C.  Head  overlapping  the  prothorax  ;  fore  tarsi  flattened,  consisting  of  one 
segment,  and  ciliated.  Fam.  XL — CORISID^E. 

CC.  Head  inserted  in  the  prothorax ;  fore  tarsi  normal. 

D.  Body  thick,  dorsal  aspect  of  abdomen  very  convex.     Insects  which 

swim  upon  their  back.  Fam.  XII. — NOTONECTID^E. 

DD.  Body  either  flat  or  elliptical  in  outline,  or  much  elongated ;  caudal 

end  of  abdomen  furnished  with   a   respiratory   tube  composed  of  a 

pair  of  grooved  filaments.  Fam.  XIII.— NEPIDSE. 

DDD.  Body  flat,  oval  or  ovate,  without  respiratory  filaments. 

E.  Abdomen  with  a  pair  of  strap-like  caudal  appendages  (these  ap- 
pendages are  retractile,  and  are  frequently  withdrawn  from  sight); 
legs  flattened  for  swimming.  Fam.  XIV. — BELOSTOMATID^E. 

EE.  Abdomen  without  caudal  appendages;  legs  fitted  for  crawling 
rather  than  swimming.  Fam.  XV. — NAUCORIDAE. 

BB.  Two  ocelli  present;  insects  aerial,  although  living  near  the  water  ;  body 
short  and  broad  ;  eyes  very  prominent.  Fam.  XVI. — "GALGULID^:. 

AA.  Antennae  prominent,  free,  rarely  (Phymatidae)  fitting  in  a  groove  under 
the  lateral  margin  of  the  pronotum. 
B.  Body  linear;  head  as  long  as  the  three  thoracic  segments. 

Fam.  XX.— LIMNOBATID^E. 

BB.  Body   of  various  forms,  but,  when  linear,  with  head  shorter  than  the 
thorax. 

C.  Distal  segment  of  the  tarsi  more  or  less  bifid,  with  the  claws  inserted 
before  the  apex. 

D.  Body   usually    elongated,   prothorax    narrow ;     rostrum    4-jointed ; 
second  and  third  pairs  of  legs  extremely  long  and  slender. 

Fam.  XIX.— HYDROBATID^E. 

DD.  Body  usually  stout,  oval,  and  broadest  across  the  prothorax ;  ros- 
trum 3-jointed  ;  legs  not  extremely  long.       Fam.  XVIII. — VELIAD.E. 
CC.  Distal  segment  of  the  tarsi  entire ;  claws  inserted  at  the  end. 
D.  Antennae  4-jointed.* 

E.  Wing-covers  reticulated,  and  of  one  uniform  thin  substance 
throughout ;  very  rarely  (Piesma)  with  a  distinction  between  the 
corium  and  membrane.  Fam.  XXVI.— TINGITID^E. 

EE.  Wing-covers  of  various  forms  or  absent,  but  not  of  the  form  pre- 
sented by  the  Tingitidae.     See  Fig.  171. 
F.  Rostrum  3-jointed. 
G.  Ocelli  wanting. 

H.  Wing-covers  rudimentary,  with  only  corium  (AcanthiinaeX 

Fam.  XXVII. — ACANTHIIDJE. 

*  In  certain  families  there  are  minute  intermediate  joints  between  the  principal  joints 
of  the  antennae.    For  the  purposes  of  this  table  these  intermediate  joints  are  not  counted- 


HEMIPTERA. 


183 


HH.  Wing-covers  well  developed. 

I.  Body  linear.  Fam.  XXL— EMESID*. 

II.  Body  not  linear. 

J.  Body  greatly  flattened.  Fam.  XXV.— ARADIDJE. 

JJ.  Body  of  ordinary  form  (Saicinse). 

Fam.  XXII.— REDUVIIDJE. 

GG.  Two  ocelli  present,  though  sometimes  difficult  to  see ;  wing- 
covers  well  developed. 
H.  Wing-covers  with  embolium,  Fig.  151.     (Anthocorinae.) 

Fam.  XXVII.— ACANTHIIDJE. 
HH.  Wing  covers  without  embolium. 

I.  Rostrum  long,  reaching  to  or  beyond   the   intermediate 
coxae.  Fam.  XVII.— SALDID^:. 

II.  Rostrum  short. 

J.  Front  legs  with  greatly  widened  femora. 

Fam.  XXIV.— PHYMATID.E. 

JJ.   Front  femora  somewhat  thickened,  but  much  less  than 
half  as  wide  as  long.  Fam.  XXII.— REDUVIID^E. 

FF.  Rostrum  4-jointed. 

G.  Membrane  of  wing-covers  with  longitudinal  veins  ;  legs  either 
raptorious  or  ambulatory. 

H.  Membrane  usually  with  four  long  veins  bounding  three 
discal  cells,  which  are  often  open.  From  these  cells  diverge 
veins  all  around  and  form  several  marginal  cells  (Fig.  150); 
legs  raptorious.  Fam.  XXIII.— NABID.E. 

HH.  Membrane  with  4  or  5  simple  or  anastomosing  veins 
arising  from  the  base  ;  or  with  a  larger  number  of  veins  aris- 
ing from  a  cross  vein  at  the  base  ;  legs  ambulatory. 

I.  Ocelli  wanting  ;  membrane  with  two  large  cells  at  the  base  ; 
and  from  these  arise  branching  veins  (Fig.  153). 

Fam.  XXIX.— PYRRHOCORID^:. 

II.  Ocelli  present. 

J.  Head  with  a  transverse  incision  in  front  of  the  ocelli. 

Fam.  XXXI.— BERYTID^:. 
JJ.  Head  without  transverse  incision. 

K.  Membrane  with  4  or  5  simple  veins  arising  from  the 
base  of  the  membrane;  the  two  inner  ones  sometimes 
joined  to  a  cell  near  the  base  (Fig.  154). 

Fam.  XXX.— LYG^ID^:. 

KK.  Membrane  with  many,  usually  forked,  veins,  spring- 
ing from  a  transverse  basal  vein  (Fig.  155). 

Fam.  XXXII.—  CoREiafc. 

GG.  Membrane  of  wings-covers  with  one  or  two  closed  cells  at 
its  base,  otherwise  without  veins  (Fig.  152);  legs  ambulatory. 

Fam.  XXVIII.-CAPSiM. 

GGG.  Membrane  of  wing-covers  without  any  veins ;  legs  ambu- 
latory. Fam.  XVIII.— HEBRIDES. 


I84 


AN  INTRODUCTION    TO   ENTOMOLOGY. 


DD.  Antennae  5-jointed.* 

E.  Lateral  margin  of  scutellum  with  a  furrow  in  which  the  edge  of 
the  wing-cover  fits  when  closed. 
F.  Scutellum  nearly  flat,  attenuated  posteriorly. 
G.  Tibiae  unarmed  or  furnished  with  very  fine  short  spines. 

Fam.  XXXIII.— PENTATOMID^:. 
GG.  Tibiae  armed  with  strong  spines  in  rows. 

Fam.  XXXIV.-CYDNiD^:. 
FF.   Scutellum  very  convex,  covering  nearly  the  whole  abdomen. 

Fam.  XXXV. — CORIMEL^ENID^E. 

EE.  Lateral  margin   of   the  scutellum  without  a  furrow  ;  scutellum 
very  convex,  covering  nearly  the  whole  abdomen. 

Fam.  XXXVL— SCUTELLERID^E. 


FIG.  150.  —  Na-    FIG.  151.  —  An-    FIG.  152.  —  Cap-    FIG.  153.  —  Ffyr-    FIG.  154.  —  Lygce-      FIG.  155.  —  Co- 
bidce.  thocorince,  sidce.  rhocoridce.  idte.  reidce. 


Family  XL  — 

(  Water-boatmen^] 

To  the  Corisidce  belong  certain  aquatic  Hcteroptera  which  are 
very  widely  and  commonly  distributed  throughout  our  country. 
They  are  of  medium  or  small  size,  and  of  somewhat  elongated  oval 
form.  They  occur  in  lakes,  ponds,  and  streams,  in  both  stagnant 
and  running  water,  and  even  in  the  salt  lakes  of  Utah  and  Califor- 
nia. 

All  of  the  North  American  species  of  this  family  belong  to  the 
genus  Corisa.  Fig.  156,  which  represents  a 
species  of  Corisa,  illustrates  the  form  of  the 
body.  These  insects  may  be  distinguished  by 
the  peculiar  tarsi  of  the  front  legs.  These 
tarsi  are  flattened  or  scoop-like  in  form  ;  each 
consists  of  a  single  segment,  and  bears  a  comb- 
like  fringe  of  bristles!  The  structure  of  the 
head  of  these  insects  is  quite  unusual.  In- 
stead of  being  inserted  in  the  prothorax,  the 
head  overlaps  that  segment.  The  position  of 
the  mouth-parts  is  also  peculiar  ;  these  are  pushed  through  an  open- 

*  In  certain  families  there  are  minute  intermediate  joints  between  the  principal  joints 
of  the  antennae  ;  for  the  purposes  of  this  table,  these  intermediate  joints  are  not  counted. 
t  Corlsidse,  Corisa:  coris  (KoptS),  a  bug. 


FIG.  156.— Corisa  undulata. 


HEMIPTERA.  185 

ing  in  the  clypeus  instead  of  being  articulated  to  its  tip.  In  the 
males  of  Corisa  the  abdominal  segments,  especially  the  four  caudal 
ones,  are  very  unsymmetrical,  being  upon  one  side  broken  into 
irregular-shaped  fragments. 

These  water-boatmen  have  the  body  flattened  above,  and  swim 
upon  their  ventral  surface  ;  they  differ  in  these  respects  from  the 
members  of  the  next  family.  They  swim  with  a  quick,  darting  mo- 
tion ;  they  use  for  this  purpose  chiefly  their  long,  oar-like  posterior 
legs.  When  in  their  favorite  attitude,  they  are  anchored  to  some 
object  near  the  bottom  of  the  pond  or  aquarium  by  the  tips  of  their 
long,  slender,  intermediate  legs,  at  such  times  the  fore  legs  hang 
slightly  folded,  and  the  posterior  legs  are  stretched  out  horizontally 
at  right  angles  to  the  length  of  the  body.  The  body  of  these  in- 
sects with  the  air  which  clings  to  it  is  much  lighter  than  water; 
consequently,  whenever  they  loose  their  hold  upon  the  object  to 
which  they  have  been  clinging,  they  rise  quickly  to  the  surface,  un- 
less they  prevent  it  by  swimming.  They  occasionally  float  on  the 
surface  of  the  water,  and  can  leap  into  the  air  from  the  water  and 
take  flight. 

The  bodies  of  these  insects,  as  they  swim  through  the  water,  are 
almost  completely  enveloped  in  air.  The  coating  of  air  upon  the 
ventral  surface  and  sides  can  be  easily  seen,  for  it  glistens  like  silver. 
By  watching  the  insects  carefully,  when  they  are  bending  their  bod- 
ies, air  can  be  seen  to  fill  the  spaces  between  the  head  and  prothorax, 
and  between  the  prothorax  and  mesothorax.  The  space  beneath 
the  wings  is  also  filled  with  air.  When  these  insects  are  in  impure 
water,  they  must  come  to  the  surface  at  intervals  to  change  this  sup- 
ply of  air.  But  I  have  demonstrated  that  in  good  water  it  is  not 
necessary  for  them  to  do  this.  The  air  with  which  the  body  is 
clothed  is  purified  by  contact  with  the  fine  particles  of  air  scattered 
through  the  water ;  so  that  the  insect  can  breathe  its  coat  of  air  again 
and  again  indefinitely.* 

The  Water-boatmen  are  carnivorous,  feeding  upon  other  insects. 
They  attach  their  eggs  to  aquatic  plants ;  and  the  young  are  found 
in  the  same  situations  as  the  adults. 

"  In  Mexico,  the  eggs  of  a  species  oicorisa  are  said  to  be  gathered 
from  water-plants,  and  used  as  an  article  of  food  by  the  dwellers 
near  the  lakes  where  they  abound.  The  natives  cultivate  a  sedge 
upon  which  the  insects  will  deposit  their  eggs.  This  sedge  is  made 

*  See  account  of  my  experiments  in  American  Naturalist,  June,  1887. 


1 86  AN  INTRODUCTION    TO  ENTOMOLOGY. 

into  bundles,  which  are  then  floated  in  the  water  of  a  lake  until  cov- 
ered with  eggs.  The  bundles  are  then  taken  out,  dried,  and  beaten 
over  a  large  cloth.  The  eggs  being  thus  disengaged,  are  cleaned  and 
pounded  into  flour."  (Glover.) 


Family  XII.— NOTONECTID^E.* 
(Back-swimmers  or  Back-swimming'  Water-boatmen^) 

The  Notonectidce  differ  from  all  other  aquatic  Heteroptera  by  the 
fact  that  they  always  swim  on   their  back.     And  there  is  a  corre- 
sponding  difference  in  the  form  of  the  body.     This  is  much  deeper 
than  in  the  allied  families,  and  is  more  boat-shaped. 
The  back,  from  the  peculiar  attitude  of  the  insect 
when  in  the  water,  corresponds  to  the  bottom  of  a 
boat,   and    is  sloped  so  as  to  greatly  resemble    in 
form  this  part  (Fig.  157). 
FlG>   undui%a™ect*  The    eyes  are  large,  uniform,    twice    sinuated 

on  the  outer  side,  and  project  a  little  way  over 
the  front  margin  of  the  prothorax.  The  prothorax  has  the 
lateral  margins  sharp  and  projecting.  The  legs  are  all  long  ;  the 
hind  pair  are  much  the  longest  and  fitted  for  swimming. 
The  tarsi  consist  each  of  three  segments,  but  the  basal  segment 
is  so  small  that  it  is  often  overlooked.  There  is  a  ridge  along  the 
middle  line  of  the  venter  which  is  clothed  with  hairs. 

These  insects  are  predaceous,  feeding  upon  insects  and  other 
small  animals.  In  collecting  them,  care  must  be  taken  or  they  will 
inflict  painful  stings  with  their  sharp  and  powerful  beak. 

The  favorite  attitude  of  the  Back-swimmers  is  floating  at  the 
surface  of  the  water,  with  the  caudal  part  projecting  sufficiently  to 
admit  of  the  air  being  drawn  into  the  space  beneath  the  wings. 
When  in  this  position,  their  long  oar-like  hind  legs  are  stretched  out- 
ward and  forward  ready  for  action.  When  disturbed,  they  dart 
away  toward  the  bottom  of  the  pond,  carrying  a  supply  of  air  for 
respiration  beneath  their  wings.  As  in  the  Corisidae,  the  body  of 
these  insects  with  the  air  which  they  carry  for  respiration  is  much 
lighter  than  water  ;  consequently,  the  moment  they  stop  swimming, 
they  rise  to  the  surface  of  the  water  if  they  do  not  cling  to  some 
object  to  prevent  it.  Occasionally  these  insects  will  float  on  the 
surface  of  the  water  with  their  dorsal  aspect  uppermost ;  and,  like  the 


*  Notongctidae,  Notongcta:  notes  (vc5ro?),  back;  nectos  (vrjKro^,  swimming. 


I1EM1PTERA.  jg7 

Water-boatmen,  they  can  leap  into  the  air  from  the  water  and  take 
flight. 

There  are  three  genera  in  North  America.  The  greater  number 
of  our  common  species  belong  to  Notonecta.  The  following  table  of 
the  genera  is  from  an  unpublished  work  by  Professor  H.  E>  Sum- 
mers : 

A.  Apices  of  hemelytra  entire  ;  the  three  pairs  of  legs  similar  in  shape.   PLEA. 
AA.  Apices  of  hemelytra  notched  ;  legs  dissimilar. 

B.  Hemelytra  much  longer    than  abdomen;    fourth  segment  of    antennae 

longer  than  third.  ANISOPS. 

BB.  Hemelytra  but  little  longer  than  abdomen;  fourth  segment  of  antennae 

shorter  than  third.  NOTONECTA. 

Family  XIII.— NEPIM;.* 
( Water-scorpions.) 

The  members  of  this  family  can  be  distinguished  from  other 
aquatic  Heteroptera  by  the  presence  of  a  long  respiratory  tube  at 
the  end  of  the  abdomen.  This  tube  con- 
sists of  two  long  filaments,  each  with  a 
groove  on  its  mesal  side.  By  applying 
these  filaments  together  the  grooves  form 
a  tube,  which  conducts  the  air  to  two 
spiracles  situated  at  the  caudal  end  of  the 
abdomen.  By  means  of  this  apparatus 
these  insects  are  able  to  rest  on  the  bot- 
tom of  a  shallow  pond,  or  among  rubbish 
or  plants  in  water,  and  by  projecting  this 
tube  to  the  surface  obtain  what  air  they 
need. 

With  regard  to  the  form  of  the  body 
two  very  different  types  exist  in  this  fam- 
ily. In  one,  represented  by  the  genus 
Nepa,  the  body  is  a  long-oval,  flat  and  thin; 
in  the  other,  represented  by  the  genus 
Rdnatra,  the  body  is  almost  linear  and 

J  FIG.  158. — Kanatra  fusca. 

cylindrical    (Fig.   158). 

The  Water-scorpions  are  carnivorous ;  and  with  them   the  first 
pair  of   legs   is    fitted   for  seizing  prey.      In   these  legs   the   coxae 

*  Ngpidae  :  Nepa,  a  scorpion. 


1 88  AN  INTRODUCTION    TO   ENTOMOLOGY. 

are  very  long,  especially  in  Ranatra :  the  femora  are  furnished  with 
a  groove  into  which  the  tibiae  and  tarsi  fit  like, the  blade  of  a  pocket- 
knife  into  its  handle. 

Although  the  Nepidae  are  truly  aquatic  insects,  the  second  and 
third  pairs  of  legs  are  fitted  for  walking  rather  than  swimming. 

Of  the  genus  Nepa  we  have  only  a  single  species,  N.  apiculata. 
This  insect  is  about  two-thirds  of  an  inch  in  length,  not  includ- 
ing the  respiratory  tube,  which  measures  a  little  more  than  one- 
fourth  of  an  inch.  It  lives  beneath  stones  and  rubbish  in  ponds, 
and  in  the  quiet  parts  of  our  streams. 

Of  the  genus  Ranatra,  our  most  common  species  is  R.  fusca 
(Fig.  158).  This  insect  .lives  in  the  same  situations  as  Nepa.  Owing 
to  the  linear  form  of  its  body,  and  to  the  dirt  with  which  it  is 
usually  covered,  it  is  quite  difficult  to  detect  the  presence  of  this 
insect  among  the  rubbish  where  it  is  found.  Doubtless  this  resem- 
blance to  a  dirty  stick  aids  it  greatly  in  the  capture  of  insects,  fish, 
and  other  unwary  animals  upon  which  it  preys. 


Family  XIV. — BELOSTOMATID^:.* 
(Giant   Water-bugs.) 

"  The  family  Belostomattda  contains  the  largest  Heteroptera  now 
in  existence.  These  are  all  wide  and  flat-bodied  aquatic  insects,  of 
more  or  less  ovate  outline,  furnished  with  powerful  flattened  swim- 
ming-legs, the  fore  tibiae  curved  as  in  the  preceding  family,  and  fitted 
for  seizing  and  holding  tightly  the  victims,  upon  which  they  pounce 
from  their  hiding  places  in  the  rubbish  or  among  the  branches  of 
water-plants.  A  remarkable  feature  of  all  the  genera  is  in  the  pres- 
ence of  a  pair  of  flattened,  narrow,  strap-like  appendages  at  the  end  of 
the  body,  which  are  extensile,  but  not  concerned  with  respiration,  as 
in  members  of  the  foregoing  group".  (Uhler.) 

These  insects  are  rapacious  creatures,  feeding  on  other  in- 
sects and  small  fish.  Some  of  the  species  are  of  great  size.  One 
found  in  Guiana  and  Brazil  sometimes  measures  four  inches  in  length. 
We  have  in  our  fauna  two  common  species  of  the  larger  Giant  Water- 
bugs.  They  are  Belostoma  americdnum  zn&Bendcus grtseus.  These 
two  species  so  closely  resemble  each  other  that  they  are  commonly 
confounded. 

*Belostomatidae,  BelSstoma :  belos  (/?e'Ao5),  a  spear  ;  stoma  (crrojua),  a  mouth. 


HEMIPTERA. 


189 


Belostoma  americdnum  (Fig.  1 59)  varies  greatly  in  size.    Specimens 
before  me  as  I  write  this  range  from  44mm.  (1.75  in.)  to  60  mm.  (2.4 
in.)  in  length.     It  is  of  a  pale   dirty-brown 
color,  mottled  with  dark  brown  ;  the  ven- 
tral aspect  of  the  body  is  speckled   with 
dark   brown.      The    anterior    femora   are 
furnished  with  a  groove  for  the  reception 
of  the  edge  of  the  tibiae. 

Bendcus  griseus  can  be  distinguished 
from  Belostoma  by  the  absence  of  the 
femoral  groove.  In  Benacus  the  ventral 
aspect  of  the  thorax  is  marked  by  five 
interrupted  longitudinal  stripes  of  dark 
brown. 

To  the  genus  Zditha  belong  our  more 
common  representatives  of  the  smaller 
members  of  this  family.  The  common 
species  of  the  Eastern  United  States  is 

ZditJia    flummea.         This    measures      about      FIG.  159.— Belostoma  americanum. 

nine-tenths  of  an  inch  in  length,  and  bears 

a  round  scar  on  each  side  of  the  prothorax  (Fig.  160).  The 
females  of  this  species  lay  their  eggs  upon 
their  own  backs.  These  eggs  are  set  upon 
end,  and  placed  in  transverse  rows,  by  means  of 
a  long  protrusile  tube  or  ovipositor,  which  the 
insect  can  extend  far  over  her  own  back.  The 
eggs  are  fastened  to  the  back  of  the  mother  by 
a  very  thin  layer  of  a  waterproof  gum  secreted  by 
the  insect.  At  about  the  time  when  the  young 
brood  begins  to  hatch,  the  mother  sheds  the 
entire  layer  of  eggs  from  her  back.  (Dim- 
mock.) 


FIG.  \(x>.—Zaithci  flu- 
minea. 


Family  XV.— 

The  Nancorida  includes  flat-bodied,  chiefly  oval  insects,  which 
are  of  smaller  size  than  the  members  of  the  preceding  family.  The 
abdomen  is  without  caudal  appendages  ,and  the  legs  are  suited  for 
crawling  rather  than  for  swimming.  The  front  legs,  however,  are  fitted 
for  grasping,  the  femora  being  greatly  thickened.  There  are  no 


*  NaucCridae,  Naucoris  :  naus  (vavt),  a  boat ;  coris  (KoptQ,  a  bag. 


I9O  AN  INTRODUCTION    TO  ENTOMOLOGY. 

ocelli ;  the  antennse  consist  of  four  simple  segments,  are  very  short, 
and  well  concealed  beneath  the  eyes.  The  rostrum  is  three-jointed, 
and  covered  at  the  base  by  the  large,  transverse,  triangular  or  rounded 
labrum,  and  the  wing-covers  are  furnished  with  a  distinct  embo- 
lium. 

The  members  of  this  family  are  predaceous  ;  and,  according  to 
Uhler,  they  are  fond  of  reedy  and  grassy,  quiet  waters,  where  they 
creep  about  like  the  Dyticid  beetles,  creeping  and  half-swimming 
around  and  between  the  leaves  and  sprays  of  the  submerged  plants, 
and  suddenly  seizing  any  unlucky  Corisa  or  other  insect  that  happens 
to  be  within  reach. 

The  family  is  a  small  one  ;  as  yet,  less  than  fifty  species  have  been 
described.  These  are  distributed  among  twelve  genera.  Of  those 
that  occur  in  the  United  States,  only  five  species,  representing  two 
genera,  have  been  described.  But  one  of  these  is  found  in  the  States 
on  the  Atlantic  coast.  This  is  Pelocoris  femordta.  It  measures 
about  9  mm. (0.35  in.)  in  length,  and  after  death  is  pale  yellow  or 
brownish  in  color,  with  black  or  dark-brown  markings.  The  remaining 
species  are  found  in  the  Western  States,  and  belong  to  the  genus 
Ambry sus.  This  genus  differs  from  Pelocoris  in  having  the  front 
margin  of  the  prothorax  very  deeply  sinuate. 


,y 


Family  XVI.— GALGULIM). 

/ 

The  Galgulidce  is  the  concluding  member  of  the  series  of  fami- 
lies of  Heteroptera  characterized  by  short  antennae,  nearly  or  quite 
concealed  beneath  the  head.  This  family  differs  from  the  other 
families  of  the  series  in  that  the  species  present  a  pair  of  ocelli.  In 
the  more  typical  forms,  the  body  is  very  broad  and  short,  and  the 
eyes  are  prominent  and  projecting.  Fig.  161  represents 
the  characteristic  form  of  these  insects. 

The  Galgulidae  differ  from  the  other  short-horned  bugs 
in  habits.  Whilst  the  members  of  the  preceding  families 
are  truly  aquatic,  these  insects  pass  their  lives  on  the 
muddy  margins  of  streams,  or  about  the  other  parts  of 
marshes,  where  the  soil  is  moist  but  not  continuously 
submerged.  Some  of  them  make  holes  for  themselves, 
and  live  for  a  part  of  the  time  beneath  the  ground. 

This  is  a  small  family,  containing  only  about  a  score  of  known 


GalgQlidae:  galgulus,  the  witwall  or  yellow  thrush. 


HEMTPTERA.  Io/i 

species.  Of  these,  only  three,  representing  three  genera,  have  been 
catalogued  from  the  United  States.  Our  forms  can  be  separated 
by  the  following  table : 

A.   Fore-legs  stout,  fitted  for  grasping. 

B.  Anterior  tarsi  with  a  single  claw.  MONONYX 

BB.  Anterior  tarsi  with  two  claws.  GALGULUS 

AA.   Fore-legs  slender,  fitted  for  running.  PELOGONUS. 

Our  three  species  are  Mononyx  stygicus,  Gdlgulus  oculdtus,  and 
Pelogonus  americdnus.  Fig.  161  represents  the  Galgulus ;  the  Mon- 
onyx closely  resembles  this  in  form  ;  while  the  Pelogonus  is  a  smaller 
insect,  with  a  more  oblong  body,  and  of  a  velvety  black  color.  All 
of  the  species  are  predaceous. 


Family  XVII.— SALDIM:.* 

With  the  Sdldidce  we  reach  the  beginning  of  the  extensive  series 
of  families  of  Heteroptera,  in  which  the  antennae  are  prominent  and 
are  not  concealed  beneath  the  head.     In  this  family  the  insects  are 
of  small  size,  and  of   dark  colors,  with  white  or  yellow  markings. 
The  head  stands  out  free  from  the  thorax  on  a  cylindrical  base. 
The  antennae  are  four-jointed  ;  there  are  two  ocelli ;  the 
rostrum    is    three-jointed   and  very  long,  reaching   to   or 
beyond  the  middle  coxae.     The  membrane  of  the  wing- 
covers  is  furnished    with    looped  veins,  forming  four  or 
five  long  cells  placed  side  by  side.     Occasionally   there 
is  little  or  no  distinction  between  the  corium  and  mem- 
brane.    Two  forms  sometimes  occur  in  the  same  species, 
one   with  a  distinct  membrane,   and   another  with   the   membrane 
thickened  and  almost  as  coriaceous  as  the  corium  proper. 

In  regard  to  the  habits  of  the  Saldidse,  Uhler  states  as  follows : 
"  In  the  present  family  we  have  types  which,  like  Gdlgulus,  make 
holes  for  themselves,  and  live  for  a  part  of  the  time  beneath  the 
ground.  Like  the  members  of  that  genus,  too,  a  majority  of  these 
inhabit  damp  soils,  and  are  often  found  in  countless  numbers  on  the 
salt  or  brackish  marshes  of  our  sea-coasts.  Their  manners  strongly 
recall  those  of  the  Tiger-beetles  that  inhabit  the  same  places.  When 
approached,  or  in  any  way  disturbed,  they  leap  from  the  ground, 
arise  a  few  feet  into  the  air  by  means  of  their  wings,  and  alight  a 


*  Saldidae:  Salda,  a  proper  name. 


IQ2  AN  INTRODUCTION    TO  ENTOMOLOGY. 

short  distance  away,  taking  care  also  to  slip  quickly  into  the  shade 
of  some  projecting  tuft  of  grass  or  clod  where  the  soil  agrees  with 
the  color  of  their  bodies." 

About  thirty  species  have  been  described  from  the  United  States 
and  British  America.     These  all  belong  to  the  genus  Sdlda. 

Family  XVIIL— VELIAD.E.* 

The  Velladce  includes  insects  which  are  very  closely  allied  to  the 
water-striders  both  in  structure  and  habits.  In  both  families,  the 
distal  segment  of  the  tarsi  is  more  or  less  bifid,  and  the  claws  are 
inserted  before  the  apex.  These  characters  distinguish  these  two 
families  from  all  other  Heteroptera.  In  the  Veliadae  the  body  is 
usually  stout,  oval,  and  broadest  across  the  pro- 
thorax,  (Fig.  163).  The  rostrum  is  three-jointed, 
and  the  legs  are  not  extremely  long.  In  fact, 
the  legs  are  fitted  for  running  over  the  water,  in- 
stead of  for  rowing,  as  with  the  Hydrobatidae. 

The  Veliadae  "  pass  most  of  their  lives  upon 
FlG'  ^'Cou£i*govelia     the  surface  of    the   water,    but    always  near  the 
banks  of  the  stream  or  pond  ;  but  they  also  make 
excursions  beyond  the  limits  of  the  water,  and  move  with  great  free- 
dom upon  the  land/'     (Uhler.) 

Less  than  a  dozen  species  have  been  described  from  the  United 
States  ;  but  these  represent  six  genera. 

Family  XIX. — HYDROBATlD^E.f. 
( Water-striders.) 

This  family  includes  elongated  or  oval  insects  which  live  upon 
the  surface  of  water.  Several  species  are  very  abundant  on  our 
ponds  and  streams.  They  run  over  the  surface  of  the  water  very 
rapidly  ;  and,  like  the  Whirligig-beetles,  often  congregate  in  great 
numbers.  The  head  is  inserted  in  the  thorax  up  to  the  base  of  the 
eyes ;  these  are  round  and  prominent.  The  antennae  are  long,  and 
consist  of  four  segments.  "  The  thorax  usually  widens  backwards, 
and  its  thickness  is  increased  by  the  prominent  middle  and  posterior 
coxae,  which  project  beyond  the  sides.  No  scutellum  is  apparent 
(except  in  Stephania),  but  in  its  place  the  end  of  the  dorsal  plate  of 

*  Veliadae:   Velia,  a  proper  name. 

f  Hydrobatidae,  Hydrobates:  hydor  (vdoop),  water;  bates  (ftdrrj^},  one  that  treads. 


HEMIPTERA.  193 

the  mesothorax  is  scale-like,  narrowed,  rounded,  and  depressed 
around  the  tip.  Behind  this,  the  abdomen  tapers  more  or  less  to- 
wards the  last  segment,  which  is  usually  armed  each  side  with  a 
tooth-like  process.  The  under  side  of  the  body  is  generally  min- 
utely pubescent  and  sericeous  like  satin,  and  this  is  sometimes  con- 
tinued along  the  sides  of  the  thorax.  There  are  commonly  two 
forms  of  the  adult  belonging  to  the  same  species,  the  winged  and 
unwinged.  These  do  not  necessarily  co-exist.  During  some  years, 
only  the  winged  forms  appear ;  while  in  others,  and  especially  if  the 
spring  and  summer  are  cool,  the  individuals  will  all  be  unwinged. 
Often  in  sunny,  protected  places,  where  the  food  is  abundant,  all 
will  be  winged,  while,  in  exposed  localities,  the  same  species  will  be 
found  unwinged,  with,  perchance,  a  single,  more  vigorous  specimen 
winged.  In  some  parts  of  the  Southern  States  three  forms  occur, 
those  before  cited  and  another  which  has  the  wing-covers  of  scarcely 
half  length."  (Uhler.) 

The  water-striders  prefer  quiet  waters,  upon  which  they  rest,  or 
over  which  they  skim  rapidly.     They  jump  from  the  water  to  capture 
flies  or  other  insects  for  food.     Fig.  164   represents  a  species  of  Hy- 
grotrechus.     "  These    insects     stow 
themselves  away  under  the   banks 
of    streams,    in   the   mud   beneath 
leaves  or  rubbish,  or  at  the  bottom 
of  water  under  stones  and  roots  of 
trees  when  the  autumn  begins  to 
be    cold  ;    and    from    thence   they 
reappear  upon   the  surface  of    the 
water  as  soon  as  the  warm  weather 
of  spring  returns.     Soon  after  this, 

the  eggs  are  attached  by  a  sort  of  glue  to  the  leaves  and  stems 
of  aquatic  plants.  They  are  whitish  translucent,  long,  cylindrical, 
more  blunt  at  the  end  from  which  the  young  emerge  than  at  the 
somewhat  tapering,  but  round,  opposite  extremity.  If  the  weather 
continues  to  grow  warmer,  these  eggs  mature  in  about  two  weeks." 
(Uhler.) 

Five  genera  occur  in  our  fauna;  these  can  be  separate 

following  table  :  * 

A.  Body  oval,  less  than  three  times  as  long  as  broad ;  pronotum  not  longer 
than  broad. 

*  This  table  was  prepared  by  Professor  H.  E.  Summers. 


IQ4  AN  INTRODUCTION    TO  ENTOMOLOGY. 

B.  Second  segment   of   antennae   longer  than  either  the  third  or  fourth. 

METROBATES. 
BB.  Second  segment  of  antennas  shorter  than  either  the  third  or  fourth. 

STEPHANIA. 

AA.  Body  elongate,  more  than  four  times  as  long  as  broad  ;  pronotum  much 
longer  than  broad. 

B.  Antennae  longer  than  head  and  pronotum  together;  the  posterior  tibiae 
and  tarsi  together  much  longer  than  the  intermediate  tibiae. 

LIMNOPORUS. 

BB.  Antennae  shorter  than  the  head  and  pronotum  together;  the  posterior 
tibiae  and  tarsi  together  but  little  longer  than  the  intermediate  tibiae. 
C.  First  segment  of  antennae  nearly  equal  in  length  to  the  fourth. 

LlMNOTRECHUS. 

CC.  First  segment  of  the  antennae  considerably  longer  than  the  fourth. 

HYGROTRECHUS. 

Closely  allied  to  Stephdnia,  and  resembling  it  in  the  form  of  their 
bodies,  are  the  species  which  constitute  the  genus  Halobates.  These 
are  truly  pelagic  insects,  living  on  the  surface  of  the  ocean,  often 
hundreds  of  miles  from  land.  They  are  most  abundant  in  the  region 
of  calms  near  the  equator  ;  they  feed  on  the  juices  of  dead  animals 
floating  on  the  surface,  and  probably  attach  their  eggs  to  floating 
sea-weed  (Sargassum). 

Family  XX.  —  LiMNOBATiD^:.* 

The  members  of  this  family  are  very  long,  slender  insects,  with 
linear  legs  and  antennae.  The  head  is  nearly 
cylindrical,  and  longer  than  the  thorax  ;  the  eyes 
are  round,  projecting,  and  placed  a  little  nearer 
the  base  than  the  tip  of  the  head.  These  insects 
creep  slowly  upon  the  surface  of  the  water  ;  they 
carry  the  body  considerably  elevated  ;  and  are 
found  mostly  where  plants  are  growing  in  quiet 
waters.  "They  delight  to  remain  at  rest,  with 
perhaps  a  single  claw  hooked  to  some  projecting 
object.  When  disturbed,  they  move  very  slowly, 
and  seem  disposed  to  save  themselves  rather  by 
concealment  among  rubbish  or  tangled  growths 
than  by  active  movements.  The  young  forms 

FIG.  \t>$.—Limnobates  111 

Uneata.  are  so  very  slender  that  they  can  only  be  detected 

with  great  difficulty  in  the  places  to  which  they  resort."     (Uhler.) 


*  Limnobatidae,    Limnobates:   limne  (Xijuvij),  a  salt  marsh;   dates  (ftdrrj^),  one  that 
treads. 


HEMIPTERA.  195 

I  find  no  observations  regarding  the  food  of  these  insects;  but  they 
are  probably  herbivorous. 

Only  a  single  species  has  been  found  in  the  United  States.  This 
is  Limnobates  linedta.  It  is  a  small  insect  less  than  12.5  mm.  (0.5  in.) 
in  length.  The  legs  and  antennae  are  extremely  slender,  being  hair- 
like  in  form.  Fig.  165  represents  this  species  greatly  enlarged. 

Family  XXL— EMESID.E.* 

The  Emesida  includes  a  small  number  of  insects  in  which  the 
body  is  very  slender,  and  the  middle  and  hind  legs  are  thread-like. 
The  front  legs  are  less  thread-like,  and  fitted  for  grasping.  They 
suggest  by  their  form  the  front  legs  of  the  Mantidae;  the  coxa  is 
very  greatly  elongated,  more  than  four  times  as  long  as  thick;  the 
femur  spined ;  and  the  tibia  shut  back  upon  the  femur. 

This  family  is  very  closely  allied  to  the  one  following.  In 
fact,  by  some  authors  the  two  are  united.  They  agree  in  having 
the  rostrum  short,  attached  to  the  tip  of  the  head,  and  with  the 
distal  end  when  not  in  use  resting  upon  the  prosternum,  which  is 
grooved  to  receive  it.  The  great  length  of  the  fore  coxa  easily  dis- 
tinguishes this  family  from  any  of  our  species  of  the  Reduviidae, 
and  in  the  Emesidae  there  are  no  ocelli.  Only  seven  species  of  this 
family  are  catalogued  from  the  United  States. 

Our  most  familiar  representative  is  Emesa  longipes.  This  insect, 
by  its  elongated  form  and  slender  legs,  at  first  sight  reminds  one  of 
the  walking-sticks.  But  the  raptorial  fore  legs,  the  wings,  and  the 
rostrum,  really  give  this  species  a  very  different  appearance  from 
those  insects.  Its  body  measures  about  33  mm.  (1.3  in.)  in  length; 
the  middle  and  hind  legs  are  each  about  40  mm.  (1.6  in.)  long; 
while  the  narrow  wings  are  only  one-fourth  as  long  as  the  legs.  As 
indicated  by  the  structure  of  the  fore  legs,  these  insects  are 
predaceous. 

Four  genera  are  represented  in  our  fauna  ;  these  can  be  separated 
as  follows  :f 

A.  The  pre-tibise  and  pre-tarsi  together  not  shorter  than  the  pre  femora. 
B.  Eyes  large,  very  prominent ;  when  seen  from  the  side,  occupying  the  whole 

side  of  the  head.  '•  LUTEVA. 

BB.  Eyes  small,  slightly  prominent;  when  seen  from  the  side,  not  occupying 

more  than  half  of  the  side  of  the  head.  2.  CERASCOPUS. 

*  EmSsidae:  Emesa,  a  proper  name. 

f  Table  prepared  by  Professor  H.  E.  Summers. 


196  AN  INTRODUCTION    TO   ENTOMOLOGY. 

AA.  Pre-tibia  and  pre-tarsi  together  shorter  than  the  pre-femora. 

B.  Pre-tarsi  one-clawed.  3.  BARCE. 

BB.  Pre-tarsi  two-clawed.  4.  EMESA. 

Family  XXII. — REDUVIID/E.* 

The  Reduviida  is  a  large  family,  including  numerous  genera  of 
diverse  forms.  Many  of  the  members  of  it  are  insects  of  considerable 
size ;  and  some  are  gayly  colored.  They  are  predaceous,  living  on 
the  blood  of  insects.  In  some  cases,  they  attack  the  higher  animals ; 
and,  occasionally,  even  man  suffers  from  them.  As  already  stated, 
this  family  is  closely  allied  to  the  preceding.  But  the  species  differ 
from  the  Emesidae  in  having  the  body  and  legs  thicker.  The  front 
coxae  are  shorter,  being  never  more  than  two  or  three  times  as  long 
as  broad  ;  and,  in  the  case  of  the  species  found  in  the  United  States, 
two  ocelli  are  present.  These  insects  agree  with  the  Emesidae  in 
having  the  rostrum  short,  three-jointed,  attached  to  the  tip  of  the 
head,  and  with  the  distal  end,  when  not  in  use,  resting  upon  the 
prosternum,  which  is  grooved  to  receive  it. 

In  Uhler's  Catalogue  of  the  Hemiptera  of  North  America  (1886), 
fifty  genera  of  the  Reduviidae  representing  nine  sub-families,  are 
enumerated.  Only  a  few  of  the  more  familiar  species  can  be  referred 
to  in  this  place. 

The  Masked  Bed-bug-hunter,  Opsiccetus  persondtus. — The  member 
of  this  family  about  which  probably  most  has  been  written  is  the  one 
for  which  I  propose  the  popular  name  given  above.     The  species  is  a 
European  one,  and  is  described  in  nearly  all  of  the  European  text- 
books of  entomology  under  the  name  Reduvius  persondtus.    But  it  is 
now  placed  in  the  genus  Opsiccetus.   A  variety  of  this  spe- 
*•       ^          cies  occurs  in  the  Atlantic  region  of  our  country.     Fig. 
W  \J          1 66  represents  the  adult  insect.   It  measures  from  1 5— 20 
|\V/(          rnm.  (0.6-0.8  inch)  in  length.     It  is  black,  or  of   a  very 
SB^  dark   brown.     The   prothorax   is  strongly   constricted 

^JffL  in  the  middle,  rounded  in   front,  and  has  a  prominent 

\  /         groove  on  the  middle  line, 

\  ^J  I  There  are  two  marked  peculiarities  of  this  species 

which  has  caused  it  to  attract  much  attention:  first,  in 

FIG.  166.— Op 

sicoetus  per-       \^  immature  stages,  the  body  is  covered  with  a  viscid 

sonatus.  J 

substance   which    causes  particles  of    dust  and  fibres 
to    adhere  to   it ;    not    only   the    body   proper,    but    the   legs  and 

*  Reduviidae,  Reduvius:  reduvia,  a  hang-nail. 


HEMIPTERA.  !9~ 

antennae  also  are  masked  in  this  way:  second,  this  species  infests 
houses  for  the  sake  of  preying  upon  the  bed-bug.  It  feeds  also  upon 
flies  and  other  insects.  Dr.  Le  Conte,  in  writing  of  this  insect,  states 
that  it  is  remarkable  for  the  intense  pain  caused  by  its  bite ;  that, 
when  caught  or  unskilfully  handled,  it  always  stings.  In  this  case! 
the  pain  is  almost  equal  to  that  of  the  bite  of  a  snake,  and  the  swel- 
ling and  irritation  which  result  from  it  will  sometimes  last  for  a  week. 
In  very  weak  and  irritable  constitutions  it  may  even  prove  fatal. 

The  Big  Bed-bug,  Conor hinus  sanguis$gus.—C\ose\y  allied  to  the 
masked  bed-bug-hunter  is  a  large  bug  which  insinuates  itself  into 
beds  for  a  less  commendable  purpose  than  that  of  its  ally;  for  it 
sucks  human  blood  at  first  hand. 

This  insect  measures  25  mm.  (i  inch)  in  length.  It  is  black, 
marked  with  red.  The  prothorax  is  triangular,  with  a  tubercle  in 
front  on  each  side,  slightly  constricted  before  the  middle,  in  front 
with  two  raised  lines  diverging  backwards,  and  most  raised  in  front, 
margined  with  red  ;  scutellum  with  two  raised  diverging  lines  directed 
forwards  and  joined  at  the  base ;  wing-covers  with  two  triangular  red 
spots  on  each,  one  at  the  base,  the  other  near  the  middle  on  the 
outside  ;  abdomen  with  six  red  spots  on  each  side,  both  above  and 
below.  The  species  was  first  described  from  Georgia;  but  it  occurs 
also  in  the  more  Northern  and  Western  States.  It,  too,  is  re- 
markable for  sucking  the  blood  of  mammals,  particularly  chil- 
dren. Dr.  Le  Conte,  who  first  described  this  insect,  says  that 
it,  like  the  preceding  species,  inflicts  a  most  painful  wound.  And 
that  he  has  known  its  bite  to  be  followed  by  very  serious  conse- 
quences, the  patient  not  recovering  from  its  effects  for  nearly  a  year. 
He  states  his  belief  also  that  the  accounts  which  we  have  of  persons 
being  bitten  by  spiders  are  based  on  stings  of  these  or  allied  insects. 

Although  the  species  referred  to  above  will  serve  to  illustrate  the 
form  of  the  members  of  this  family,  they  are  exceptional  in  habits. 
I  know  of  no  others  that  habitually  enter  the  dwellings  of  man. 
Usually  the  members  of  this  family  pass  their  lives  upon  trees, 
shrubs,  or  herbage,  adroitly  catching  their  prey.  They  feed  upon 
various  insects  both  in  the  larva  and  adult  states.  Numerous 
instances  are  on  record  of  their  destroying  the  Colorado  potato- 
beetle,  the  Rocky  Mountain  locust,  and  other  important  pests. 

The  wheel-bug,  Prionidus  cristdtus  (Fig.  167)  furnishes  a  good 
illustration  of  the  habits  of  the  predaceous  members  -of  this  family. 
This  is  a  common  insect  in  the  South.  The  adult,  a  cluster  of  eggs, 
and  several  nymphs  are  represented  in  the  figure.  The  hexagonal 


198  AN  INTRODUCTION    TO  ENTOMOLOGY. 

masses  of  eggs  are  deposited  on  the  bark  of  trees,  on  fence-rails,  under 
the  eaves  of  out-buildings,  or  wherever  the   female  chances  to  be 


FIG.  167. — Prionidus  cristatus.    (From  Glover  ) 

at  the  time  of  oviposition,  to  the  number  of  70  or  more.  The 
nymphs  when  young  are  blood-red,  with  black  marks,  and  do  not 
resemble  the  adult  insect  excepting  somewhat  in  form  and  in  habits. 
Both  the  nymphs  and  adults  feed  upon  all  other  insects  they  can 
overcome,  not  even  sparing  their  own  kind.  "  They  kill  their  prey 
by  inserting  into  it  the  proboscis,  which  ejects  a  most  powerful 
poisonous  liquid  into  the  wound.  The  victim  thus  pierced  dies  in  a 
very  short  time.  They  then  leisurely  suck  the  juices  out,  and  drop 
the  empty  skin.  The  perfect  insect  is  of  a  gray  color,  and  has  a  high 
semicircular  ridge  or  projection  on  the  crest  of  its  thorax."  (Glover.) 

Family  XXIIL— NABID.E.* 

We  have  but  few  representatives  of  the  Nabidce ;  but  some  of 
them  are  very  common.     In  this  family  the  body  is  oblong,  and 

*  Nabidae :  Nabis,  a  proper  name. 


HEMIPTERA.  l^g 

somewhat  oval  behind.  The  rostrum  is  long,  slender,  and  four- 
jointed.  The  wing-covers  are  longer  than  the  abdomen,  or  are  very 
short.  In  the  long-winged  forms  the  membrane  is  usually  furnished 
with  four  long  veins  bounding  three  discal  cells,  which  are  often 
open.  From  these  cells  diverge  veins  all  around  and  form,  several 
marginal  cells.  (Fig.  168.) 

Only  three  genera  occur  in  our  fauna ;  these  can  be  separated  by 
the  following  table  :* 

A.  Pre-acetabula  remote  from  each  other.   Clavus  and  corium  semi-transparent. 

(Sub-family  Coriscinae.)  j    CoRiscus. 

A  A.  Pre-acetabula  close  together.     Clavus  and  corium  opaque.     (Sub-family 

Nabinse.) 

B.  Joint  2  of  rostrum  longer  than  joint  3 ;  joint  2  reaching  base  of  head. 

2.  PAGASA. 
BB.  Joint  2  of  rostrum  shorter  than  joint  3 ;  joint  2  not  reaching  base  of 

head-  3-  NABIS. 

Conscus  ferus  is  one  of  our  most  common  species.     This  insect 
measures  about  8  mm.  (0.3  in.)  in  length.     It  is  pale  yellow  with  nu- 
merous minute  brown  dots.      The  veins  of   the   mem- 
brane are  also  brownish.     This  species  is  widely  dis- 
tributed   both    in    this    country  and    in    Europe.       It 
secretes    itself   in  the    flowers  or    among    the   foliage 
of    various    herbaceous    plants,    and     captures    small 
insects  upon  which  it  feeds.     Fig.  168  represents  the 
wing-cover  of  this  species. 

Coriscus  subcoleoptrdtus  is  another  very  common  species,  and  one 
that  is  quite  likely  to  attract  attention.  Although  I  have  collected 
very  many  specimens  of  it,  I  have  met  with  only  the  short-winged 
form.  This  is  of  a  shining,  jet-black  color,  with  the  edge  of  the 
abdomen  and  the  legs  yellowish.  The  specimens  before  me  have 
short  wing-covers  which  barely  extend  to  the  second  abdominal  seg- 
ment. Uhler  says  that  the  long-winged  form  is  much  narrower 
behind,  and  the  wing-covers  and  abdomen  are  rather  dusky,  or  pice- 
ous,  than  black. 

Family  XXIV.— PHYMATlD^.f 

The  Phymatidce  is  even  more  poorly  represented  in  this  country 
than  the  preceding  family ;  but,  as  in  that  case,  some  of  the  species 

*  Prepared  by  Professor  H.  E.  Summers. 

f  Phymatidae,  Phymata:  phyma  (fiujLta),  a  tumor. 


2OO  AN  INTRODUCTION    TO   ENTOMOLOGY. 

are  very  common.  Here  we  find  the  body  extended  laterally  into 
angular  or  rounded  projections,  suggesting  the  name  of  the  typi- 
cal genus.  But  the  most  striking  character  which  distinguishes  this 
group  is  the  remarkable  form  of  the  front  legs.  These  are  fitted  for 
seizing  prey.  The  coxa  is  somewhat  elongated  ;  the  femur  is  greatly 
thickened,  so  that  it  is  half  or  two  thirds  as  broad  as  long  ;  the  tibia  is 
sickle-shaped,  and  fits  closely  upon  the  broadened  and  curved  end 
of  the  femur;  both  tibia  and  femur  are  armed  with  a  series  of  close- 
set  teeth,  so  that  the  unlucky  insect  that  is  grasped  by  this  organ 
is  firmly  held  between  two  saws  ;  the  apparently  useless  tarsus  is 
bent  back  into  a  groove  in  the  tibia.  Another  striking  character 
is  presented  by  the  antennae  :  the  terminal  segment  is  more  or  less 
enlarged  into  a  knob.  Under  the  lateral  margin  of  the  pronotum 
there  is  on  each  side  a  groove  into  which  the  antenna  fits. 

Only  two  genera  are  represented  in  our  fauna.     These  can  be 
distinguished  as  follows  : 

A.  Scutellum  short;  head  with  a  bifid  prolongation  above  the  insertion  of  the 
antennae.  PHYMATA. 

AA.  Scutellum  very  long,  extending  to  the  tip  of  the  abdomen  ;  head  without 
bifid  prolongation  of  the  antennae.  MACROCEPHALUS. 

Our  most  common  species  is  Phymata   Wolffii  (Fig.  169).     It  is 
a  yellow  insect,  greenish  when  fresh,  marked   by  a  broad 
black  band  across  the   expanded  part  of  the    abdomen. 
It  conceals  itself  in  the  flowers  of  various  plants,  and  cap- 
tures the  insects  which  come  to  sip  nectar.     It  is  remark- 
FIG  16  -       a^e  wnat   large    insects    it    can    overcome  and  destroy. 
*woiffii*     Cabbage-butterflies,    honey-bees,    and    large    wasps    are 
overpowered  by  it. 


Family  XXV.— 

The  Aradidce  are  very  easily  recognized  by  the  depressed  form 
of  the  body.  In  fact  they  are  the  flattest  of  all  Heteroptera.  They 
live  in  the  cracks  or  beneath  the  bark  of  decaying  trees  ;  and  the 
form  of  the  body  is  especially  adapted  for  gliding  about  in  these 
cramped  situations.  They  are  usually  of  a  dull  brown  color  ;  some- 
times they  are  varied  with  reddish  or  pale  markings.  Unlike  the  pre- 
ceding family,  the  legs  are  all  of  similar  form.  There  are  no 
ocelli  ;  the  antennae  are  four-jointed  ;  the  rostrum  three-jointed  ;  the 
wing-covers  are  usually  well  developed,  with  distinct  corium,  clavus, 

*  Aradidae,  Aradus:  aradus  (dpddoty,  a  violent  disturbance  of  the  stomach. 


HEMIPTERA.  2OI 

and  membrane  ;  and  the  tarsi  are  two-jointed.  The  species  are  said 
to  feed  upon  fungi.  It  is  desirable  that  observation  should  be  made 
upon  their  habits.  The  family  is  not  a  large  one.  Only  a  little 
more  than  a  score  of  species  are  now  catalogued  from  the  United 
States.  They  are  of  medium  or  small  size ;  our  largest  one  meas- 
ures less  than  half  an  inch  in  length.  Fig.  170,  Aradus 
aciitus,  will  serve  to  represent  the  form  characteristic  of 
the  family. 

Our  genera  can  be  separated  by  the  following  table  :* 

A.   Rostrum  reaching  only  about  to  base  of  head;  ventral   surface        Fic.i7o.- 
of  thorax  and  abdomen  not  furnished  with  a  fine  mesal  furrow. 

(Sub-family  BRACHYRHYNCHINJE). 

B.  Joint  4  of  antennae  much  longer  than  joint  3  ;  scutellum  transverse,  broad 
caudad,  caudal  angle  obtusely  rounded.  i.  ANEURUS. 

B.  Joint  4  of  antennae  not  longer  than  joint  3  ;  scutellum  scarcely  transverse, 

triangular,  caudal  angle  acute.  2.  BRACHYRHYNCHUS. 

AA.   Rostrum  reaching  about  to  caudal  margin  of  prosternum  or  beyond  it ; 

ventral  surface  of  abdomen  and  thorax  furnished  with  a  fine  mesal  furrow. 

(Sub-family  Aradinae.)  ARADUS. 

Family  XXVI.—TlNGITID^.f 

The  Tingitidce  are  doubtless  the  most  easily  recognized  of  all 
Heteroptera.     The  reticulated  and  gauze-like  structure  of  the  wing- 
covers,  usually  accompanied  by  expansions  of  the  prothorax  of  a 
similar  form,  gives  these  insects  a  characteristic  appearance  which 
needs  only  to  be  once  seen  to  be  recognized 
in   the    future.      Fig.    171   represents   one  of 
these    insects    greatly  enlarged,  the  hair-line 
at  the  side  indicating  the  natural  size  of  the 
insect.     They  are  generally  very  small  insects. 
But    they   occur   in    great    numbers    on   the 
leaves  of  trees  and  shrubs. 

In  this  family  the  ocelli  are  wanting;  the 
rostrum  and  the  antennae  are  both  four- 
jointed;  the  scutellum  is  wanting  or  rudi- 

FIG.  ^.-corythuca  arcu-      mentary,  replaced  by  the  angular  hind  portion 
^.    (From  the  Author's        f    ^    pronotum ;    and    the    tarsi    are   two- 

Report  for  1879.) 

jointed. 
The  family  is  one  of  considerable  size.     There  are  about  forty 

*  This  table  was  prepared  by  Professor  H.  E.  Summers, 
f  Tingltidae  .   Tlngis,  a  proper  name. 


202  AN  INTRODUCTION    TO   ENTOMOLOGY. 

known  genera,  including  hundreds  of  species.  Less  than  a  score  of 
species  are  now  catalogued  from  the  United  States  ;  but  doubtless 
many  more  will  be  found. 

There  are  two  well-marked  sub-families. 


Sub-family  I.  — 

This  division  includes  nearly  all  of  the  known  species.  Here  the 
scutellum  is  usually  covered  by  an  angular  projection  of  the  pro- 
notum  ;  and  the  wing-covers  have  no  distinction  between  the  clavus, 
corium,  and  membrane. 

The  genera  that  occur  in  the  United  States  can  be  separated  by 
the  following  table:* 

A.  Discoidal   and  costal   areas  of  hemelytra  rarely  jointly  elevated  ;  when  so 
elevated,  the  lateral  margins  of  pronotum  never  broadly  foliaceous,  nor  with 
the  narrow  foliaceous  parts  (when  they  are  present)  produced  cephalad. 
B.  Rostral  sulcus  of  the  sternum  not  interrupted  by  a  transverse  ridge  (be- 
tween the  mesosternum  and  metasternum). 

C.  Costal  area  of  hemelytra  furnished  with  a  regular  single   or  double 
series  of  areoles. 

D.  Costal  area  with  a  single  series  of  areoles.  i.  TELEONEMIA. 

DD.  Costal  area  with  a  double  series  of  areoles.  2.  TYNGis. 

CC.  Costal  area  of   hemelytra,  at  least  in  part,  furnished  with  a  triple  or 
multiple,  sometimes  confused,  series  of  areoles. 
D.  Joint  i  of  antennae  not  twice  as  long  as  joint  2. 
E.  Pronotum  with  a  single  longitudinal  mesal  ridge  (carina)  ;  third 
joint  of  antennae  not  at  all  slender.  3.  LEPTOYPHA. 

EE.  Prosternum  with  three  parallel  longitudinal  ridges  (carinae)  ;  third 
joint  of  antennae  slender.  4.  PHYSATOCHILA. 

DD.  Joint  i  of  antennae  at  least  twice  as  long  as  joint  2. 
E.  Oblong,  anal  margins  of  hemelytra  somewhat  concave. 

5.  LEPTOSTYLA. 

EE.  Oval,  anal  margins  of  hemelytra  convex.  8.  ACALYPTA. 

BB.  Rostral  sulcus  of  the  sternum  interrupted  between  the  mesosternum 

and  metasternum  by  a  transverse  ridge.  6.  GARGAPHIA. 

AA.  Discoidal  and  costal  areas  of  hemelytra  jointly  elevated  ;  lateral  margins 

of  pronotum  broadly  foliaceous,  produced  cephalad.  7.  CORYTHUCA. 

The  following  species  will  serve  as  an  illustration  of  this  sub- 
family. 

The  Hawthorn  Tingis,  Corythuca  arcudta.  —  This  I  found  very 
abundant  in  Washington,  puncturing  the  under  surface  of  the  leaves 

*  Prepared  by  Professor  H.  E.  Summers. 


HEMIPTERA.  203 

of  different  species  of  Crat&gus.  The  infested  leaves  have  a  brown 
and  sunburnt  appearance.  All  stages  were  found  together.  The 
adult  is  represented  much  enlarged  by  Fig.  171.  In  Fig.  172  the 
eggs  and  immature  form  are  shown.  The  eggs  are 
smooth,  whitish,  glistening,  semitransparent,  and 
ovoid  in  shape.  Their  average  length  is  3  mm. 
(0.12  in.).  They  are  deposited  on  their  broad  end, 
and  seem  to  be  somewhat  inserted  into  the  sub- 
stance of  the  leaf ;  they  are  covered  completely 
by  a  brown,  sticky  substance,  which  hardens  soon 
after  oviposition.  It  adheres  so  firmly  to  the  egg, 
especially  to  the  upper  portion,  that  it  is  impos- 
sible to  remove  it  without  crushing  the  egg. 

,     ,  &&         FIG.    172.  —  Eggs    and 

At  its  upper  end  this  covering  of  the  egg  is  squarely       nymph  of  corytkuca 

.     .  ,  .  '  arcuata.      (From  the 

truncate,  giving  the  whole  mass  the  appearance  Author*!  Report  for 
of  a  frustum  of  a  cone  with  a  porous  lid.  From 
the  funnel-shaped  summit  the  young  insect  makes  its  exit.  The  eggs 
are  usually  laid,  in  groups  of  from  ten  to  thirty,  along  both  sides  of 
some  prominent  leaf  vein.  They  bear  a  much  greater  resemblance 
to  certain  forms  of  fungi,  notably  the  genus  Phoma,  and  to  certain 
young  Homopterous  galls,  than  they  do  to  eggs  of  any  sort. 

The  immature  insect  is  of  the  same  dirty  brown  color  as  the  sub- 
stance covering  the  egg,  and  but  little  darker  than  the  withering 
leaf.  It  is  of  a  broad,  flat,  oval  shape,  and  spines  seem  to  project 
from  almost  every  portion  of  its  body.  It  looks  under  the  micro- 
scope more  like  a  lobe  of  prickly  cactus  than  anything  else  I  can 
think  of.  The  cast-off  skins  stick  to  the  leaf,  and  give  it  the  appear- 
ance of  being  much  more  seriously  infested  than  it  really  is. 

The  dead  leaves  under  the  bushes  during  the  winter  have  been 
often  found  to  contain  the  living  and  healthy  eggs  of  the  Tingis ; 
but  the  customary  method  of  hibernation  is  in  the  adult  state  alone. 
This  form  can  be  found  during  the  winter  under  the  loose  bark  of 
the  tree,  and  under  sticks  and  stones  on  the  ground.  These  insects 
can  be  destroyed  by  strong  alkaline  washes  or  by  kerosene  emul- 
sions. But  it  is  probable  that  if  the  leaves  and  rubbish  underneath 
the  trees  are  destroyed,  either  every  fall  or  every  spring,  a  necessity 
for  remedies  will  not  arise. 

Sub-Family  II.— PIESMIN.E. 

This  division  includes  a  single  aberrant  genus,  Piesma,  of  which 
but  few  species  are  known.  Here  the  scutellum  is  not  covered  ;  the 


2O4  AN  INTRODUCTION    TO  ENTOMOLOGY. 

wing-covers  have  a  distinct  clavus,  with  a  well-marked  claval  suture ; 
the  clavus  is  furnished  with  one,  and  the  corium  with  three  longi- 
tudinal veins  which  are  much  stronger  than  the  network  of  veins 
between  them.  In  long-winged  specimens  the  tip  of  the  membrane 
lacks  the  network  of  veins  and  appears  like  the  membrane  in  other 
families.  As  yet  but  a  single  American  species  has  been  described. 
The  Ash-gray  Leal-bug,  Piesma  cinerea. — This  measures  about 
3  mm.  (0.12  in.)  in  length,  and  is  of  an  ash-gray  color.  The  prothorax 
is  deeply  pitted,  so  that  it  presents  the  same  appearance  as  the  base 
of  the  wing-covers.  The  head  is  deeply  bifid  at  tip,  and  there  is  a 
short  robust  spine  between  the  eye  and  antenna  of  each  side.  This 
species  sometimes  infests  vineyards  to  an  injurious  extent,  destroy- 
ing the  flower-buds  in  early  spring. 

Family  XXVII.— AcANTHIIM).* 

The  Acanthiidae  comprises  two  closely  allied  groups,  which  have 
been  considered  as  distinct  families,  but  are  now  ranked  as  sub- 
families. These  are  the  Acanthimce  and  ti\zAnthocorin<%.  As  these 
have  been  separated  in  the  table  of  families,  I  will  at  once  proceed  to 
the  discussion  of  them. 

Sub-Family.  I.— ACANTHIIN.E. 
(Bed-bugs?) 

The  Acanthiince  is  represented  in  this  country  by  a  single  species, 
the  Bed-bug,  Acdnthia  lectuldria.  This  species  is  a  well-known  pest 
over  the  greater  part  of  the  world.  It  is  reddish-brown  in  color,  and 
measures  in  length  when  full  grown  from  4  to  5  mm.  (0.16  to  .018  in.). 
It  presents  the  following  characters,  which  are  those  of  the  sub-family 
Acanthiinae:  The  body  is  ovate  in  outline  and  is  very  flat  (Fig. 
173).  It  is  wingless  or  with  very  short  and  rudimen- 
tary wing-covers.  The  labrum  is  triangular.  There 
are  no  ocelli.  The  rostrum  consists  of  three  seg- 
ments ;  the  antennae,  of  four ;  and  the  tarsi,  of 
three. 

The  bed-bug  is  a  nocturnal  insect,  hiding  by  day 
in    the    cracks   of    furniture    and   beneath   various 
objects.       Ordinarily    it   is   found   only  in    the  dwellings    of    man. 
But    it    has    been    known,    to   infest    chicken-coops    and    pigeon- 

*  Acanthiidae,  Acanthia  :  acdntha  (aKCLv^a),  a  thorn. 


HEMIPTERA.  205 

houses.  And  the  opinion  is  held  that  it  also  infests  bats  and 
may  be  brought  into  our  dwellings  by  these  creatures.  I  have, 
however,  found  no  well-authenticated  instance  of  its  occurring 
upon  these  animals,  or  of  its  being  found  in  saw-dust,  or  under  the 
bark  of  trees,  as  has  been  reported.  The  means  commonly  employed 
to  destroy  this  pest  is  to  wet  the  cracks  of  the  bedstead  and  other 
places  in  which  it  hides  with  corrosive  sublimate  dissolved  in  alcohol. 
This  is  sold  by  druggists  under  the  name  of  bed-bug  poison.  As 
this  substance  is  a  virulent  poison,  it  should  be  used  with  great  care. 
A  safer  substance  to  use  is  Pyrethrum.  In  case  of  a  badly  infested 
room,  it  should  be  thoroughly  cleaned  ;  fumed  with  sulphur ;  the 
walls  re-papered,  kalsomined,  or  whitewashed  ;  and  the  wood-work  re- 
painted. In  travelling  where  one  is  forced  to  lodge  at  places  infested 
by  this  insect  or  by  fleas,  protection  from  them  can  be  had  by 
sprinkling  a  small  quantity  of  Pyrethrum  powder  between  the  sheets 
of  the  bed  on  retiring. 

Sub-Family  II.— ANTHOCORIN^:.* 
(  The  Flower-bugs^} 

In  the  Anthocorlna  the  wing-covers  are  almost  always  fully  de- 
veloped;   and    are    furnished    with  an  embolium  (Fig.  174).     The 
ocelli  are  present,  though  sometimes  difficult    to   see. 
As  in  the  preceding  sub-family,  the    rostrum  consists       .sg&f ) 
of    three   segments;   the  antennae,   of   four;  and   the     C* 
tarsi,  of   three.  F  w.ng-Vov^ 

The  species  are  small.     They  are  found  in  a  great        of  THphiep*. 
variety  of  situations,  often  upon  trees  and  on  flowers, 
sometimes  under  bark  or  rubbish.     They  are  predaceous. 

Nearly  thirty  species  have  been  catalogued  from  the  United 
States.  The  best  known  of  these  is  the  Insidious  Flower-bug, 
Triphleps  insidiosus.  This  is  often  found  preying  upon  the  leaf-in- 
habiting form  of  the  Grape  Phylloxera ;  it  is  also  often  found  in  com- 
pany  with  the  Chinch-bug,  upon  which  it  preys,  and  for  which  it  is 
sometimes  mistaken. 


Family  XXVIII.— 
This  is  one  of  the  large  families  of  the  Heteroptera.    Nearly  a  hun- 
dred genera  are  catalogued  from  North  America  alone.     The  spe< 

*  Anthocorlna,  Anthocoris  :  anthos  (av&oS),  a  flower  ;  cons  (KopiS),  a  bug. 
f  Capsidze,  Capsus  :  capsus,  a  wagon-body,  an  enclosure. 

14 


2O6  AN  INTRODUCTION    TO  ENTOMOLOGY. 

are  usually  of  medium  or  small  size ;  there  is  a  great  variation  in  the 
form  of  the  body,  which  makes  it  difficult  to  characterize  the  family. 
The  most  available  character  for  distinguishing  these  insects  is  the 
structure  of  the  wing-covers.  These  are  almost  always  complete,  and 
composed  of  clavus,  corium,  cuneus,  and  membrane.  At  the  base 
of  the  membrane  there  are  one  or  two  cells ;  otherwise  the  mem- 
brane is  without  veins.  See  Fig.  175.  Other  characters  of  the  fam- 
ily are  as  follows  :  The  ocelli  are  wanting ;  the  rostrum 
and  antennae  are  each  four-jointed  ;  the  coxae  are  sub- 
elongate  ;  and  the  tarsi  are  three-jointed. 

It  is  impracticable   to  discuss  here  the   divisions  of 
-cover      this    family  ;    I  can    only  refer  to  a  few  of  the  more 
oiP^ocap.      common  species. 

The    Fourrlined  Leaf-bug,  Poecilocdpsus  linedtus. — 
This  is  a  bright  yellow  bug,  marked  with  black.     It  measures  about 
8  mm.  (0.31  in.)  in  length.     There  are  four  longitudinal  black  lines 
which    extend    over   the   prothorax    and   the  greater  part    of    the 
wing-covers  (Fig.  176).     There  is  in  many  specimens 
a  black  dot  on  the  cuneus  of    each  wing-cover ;  and 
the  membrane  is   also    black.      This    insect    infests 
various  plants,  but   abounds  most  on  the  leaves  of 
currant-bushes    and    of    sage.       It    punctures    the 
young   and    tender    leaves,    causing     small    brown        FlG 
spots ;    but    these  are  sometimes   so  numerous  and          Tu 
closely  placed  that  the    leaves  become    completely 
withered.    This  insect  is  sometimes  very  abundant  during  the  spring 
and  early  summer :  and  occasionally  does  great  injury.     No  efficient 
means  of  destroying  it  has  been   devised   except  to    collect   it  by 
jarring  the  bushes  early  in  the  morning  while  it  is  torpid. 

The  Tarnished  Plant-bug,  Lygus pratensis. — The  Tarnished  Plant- 
bug  is  a  very  common  member  of  the  Capsidae.  It  is  smaller  than 
the  preceding  species,  measuring  5  mm.  (0.2  in.)  in  length,  and  2j  mm. 
(o.i  in.)  in  its  greatest  width.  It  is  exceedingly  variable  in  color  and 
markings.  It  ranges  from  a  dull  bark  brown  to  a  greenish  or  dirty 
yellowish  brown.  In  the  more  typical  forms  the  prothorax  has  a 
yellowish  margin  and  several  longitudinal  yellowish  lines ;  there  is 
a  V-shaped  yellowish  mark  on  the  scutellum ;  the  distal  end  of  the 
corium  is  dark  ;  and  the  cuneus  is  pale,  with  a  black  point  at  the  apex. 
This  species  has  been  reported  as  injuriously  infesting  the  young 
leaves  of  the  expanding  buds  of  pear,  and  also  the  unopened  buds. 
Sometimes  a  whole  branch  will  be  thus  affected,  and  will  die  as  the 


HEMIPTERA. 


207 


result  of  the  injury.  This  species  passes  the  winter  in  the  adult  state. 
When  it  becomes  injurious,  the  insects  should  be  shaken  from  the 
trees  upon  a  sheet,  early  in  the  morning,  while  they  are  torpid,  and 
destroyed. 

The  most  abundant  species  of  the  Capsidae  in  the  Northeastern 
United  States  is  one  for  which  I  know  no  popular  name,  Leptoptcrna 
dolobrata.  In  sweeping  the  grass  of  meadows,  in  early  summer,  in 
this  locality,  frequently  more  specimens  of  this  bug  are  taken  than 
of  all  other  insects.  This  species  is  very  different  in  form  from  the  two 
preceding,  the  body  being  long  and  narrow.  Fully  developed  speci- 
mens measure  9  mm.  (0.4  in.)  to  the  tip  of  the  wing-covers ;  and  are  but 
little  more  than  2  mm.  (.08  in.)  in  width.  The  color  is  greenish 
yellow  marked  with  black.  The  markings  of  the  head  vary  greatly  ; 
there  are  two  longitudinal  black  stripes  extending  from  the  eyes 
over  the  prothorax  and  scutellum.  The  central  part  and  apex  of 
the  scutellum  is  light-colored.  There  is  a  variety  in  which  the  cor- 
neous part  of  the  wing-covers  is  rust-red. 

Family  XXIX.— PYRRHOCORID^:.* 

The  members  of  this  family  are  very  different  in  appearance  from 
those  of  the  preceding  family.     They  are  larger,  stouter,  and  more 
heavily  built,  and  are  generally  marked  with  strongly   contrasting 
colors ;  red  with  black   or  brown  are  the  most  usual 
combinations.    In  coloring  these  insects  resemble  some     ^§^=33^^ 
of   the   larger  species    of   the  following  family.     The     ^^S^^ 
Pyrrhocoridae  can  be  distinguished  from  the  Lygaeidae     FiG.i77.-wing- 
by  the  absence  of  ocelli,  and  by  the  peculiar  venation       S^L°£  Dy*' 
of  the  membrane  of   the  wing-covers  (Fig.  177).      At 

the  base  of  the  membrane  there  are  two  large  cells ; 

and  from  these  arise  branching  veins.     Only  twenty- 

¥five  species  of    this  family  are  catalogued  by  Uhler 
from    North    America ;  and  of   these  but   seven   are 
credited  to  the  United    States.     Our  forms  occur  in 
the  Southern  and  Western  States. 
Our   most  important  species,  from   an   economic 
standpoint,  is  the  Red-bug  or  Cotton-stainer,  Dysdtrcus 
Vlcusll^reyiius^     suturtllus.     This  species  serves  well  as  an  illustration 
of   the  appearance  of    the  members  of    this    family 
(Fig.  178).     "  It  is  oblong-oval  in  form,  of  a  red  color;  the  wing-cov- 

*Pyrrhoc6rid<e,  PyrrhScoris  :  pyrrhos  (rtvppoS),  reddish  ;  coris(Kopi$\  bug. 


208  AN  INTRODUCTION   TO  ENTOMOLOGY. 

ers  and  an  arc  on  the  base  of  the  prothorax,  and  also  the  scutellum, 
are  pale  brown.  The  wing-covers  have  the  costal  margin,  a 
narrow  line  bordering  the  base  of  the  membrane  and  continuing 
diagonally  along  the  outer  margin  of  the  clavus,  and  also  a  slender 
streak  on  the  inner  margin  of  the  clavus,  pale  yellow.  It  varies 
much  in  size,  ranging  from  10  mm.  to  16  mm.  (0.4  in.  to  0.63  in.)  in 
length."  From  time  immemorial  this  has  been  one  of  the  worst 
pests  with  which  the  cotton-planters  of  Florida  and  the  West  Indies 
have  had  to  contend  ;  it  would  be  difficult  to  estimate  the  immense 
loss  it  has  occasioned.  It  does  much  damage  by  piercing  the  stems 
and  bolls  with  its  beak  and  sucking  the  sap,  but  the  principal  injury 
to  the  crop  is  from  staining  the  cotton  in  the  opening  boll  by  its  ex- 
crement. I  found  also  in  Florida  that  this  insect  is  sometimes  very 
injurious  to  oranges;  it  punctures  the  rind  of  the  fruit  with  its  ros- 
trum ;  and  soon  decay  sets  in,  and  the  fruit  drops.  The  principal 
injury  seems  to  have  been  done  where  cotton  was  planted  in  close 
proximity  to  the  orange-groves.  On  one  occasion  I  received  the 
eggs  of  this  insect  from  Florida ;  they  were  laid  in  a  group  of 
twenty-one  upon  the  under  side  of  an  orange-leaf.  They  were  am- 
ber colored,  and  oval  in  shape  ;  they  appeared  smooth  and  glistening 
to  the  naked  eye,  but  an  examination  with  a  lens  showed  them  to  be 
densely  covered  with  hexagonal  impressions.  The  young  bugs  are 
bright  red  with  black  legs  and  antennae.  These  insects  can  be  trapped 
in  cotton-fields  by  laying  chips  of  sugar-cane  upon  the  earth  near 
the  plants  ;  in  orange-groves  small  heaps  of  cotton-seed  will  be  found 
useful,  as  well  as  pieces  of  sugar-cane.  The  insects  which  collect 
upon  these  traps  can  be  destroyed  with  hot  water. 


Family  XXX.— LYG.EIM;.* 

The  Lygaeidae  is  another  one  of  the  large  families  of  the  Heter- 
optera.  It  includes  certain  forms  which  closely  resemble  members 
of  the  preceding  family  in  size,  form,  and  strongly  contrasting  colors. 
But  the  great  majority  of  the  species  are  of  smaller  size  and  less 
brightly  colored ;  and  all  differ  from  that  family  in  presenting  dis- 
tinct ocelli.  The  membrane  of  the  wing-covers  is  furnished  with 
four  or  five  simple  veins,  which  arise  from  the  base  of  the  mem- 
brane ;  sometimes  the  two  inner  veins  are  joined  to  a  cell  near  the 


*Lygaeidae,  Lygseus  :  lygaos  (A.vyaioS),  dark. 


HEMIPTERA.  2O$ 

base  '(Fig.  179).      The  antenna   of   each   side  is  inserted  below  an 
ideal  line    extending  from  the   eye  to  the  base  of   the 
rostrum.     And  the  vertex  is  not  constricted  in  front  of 
the  ocelli. 

There  is  a  great  variety  of  forms  in  this  family  ; 
the  North  American  species  are  distributed  among 
nearly  fifty  genera,  representing  nine  sub-families. 

The  first  sub-family,  Lygaina,  includes  the  forms,  referred  to 
above,  that  resemble  the  Pyrrhocoridae  in  coloring.  These  are  chief- 
ly red  insects,  banded  with  black  across  the  wing-covers.  Among 
our  most  common  species  are  the  three  following: 

Oncopeltusfascidtus. — This  is  a  large  red  and  black  insect,  measur- 
ing 1 6  mm.  (0.63  in.)  in  length.  It  has  the  following-named  parts 
black :  legs,  antennae,  rostrum,  sides,  and  middle  line  of  the  head, 
disk  of  the  prothorax,  scutellum,  most  of  the  ventral  aspect  of  the 
thorax,  dots  along  the  lateral  edge  of  the  abdomen,  the  tip  of  the 
abdomen,  and  two  spots  on  each  side  of  the  ventral  aspect  of  the 
same  region.  There  is  a  broad  black  transverse  band  across  the  middle 
of  the  wing-covers  ;  and  the  membrane  is  also  of  the  same  color.  This 
species  "  is  pretty  generally  distributed  throughout  the  warm  and 
sheltered  parts  of  this  continent,  and  wherever  the  larger  varieties  of 
Asclepias  flourish,  either  on  the  coast  or  inland."  (Uhler.) 

Lyg&us  reclivdtus. — This  is  smaller  than  the  preceding  species, 
measuring  from  10  to  12  mm.  (0.4  in.  to  0.47  in.)  in  length.  The 
head  is  black,  with  red  spots  on  the  vertex ;  the  thorax  is  black, 
with  a  transverse  red  band  on  the  disk  of  the  pronotum ;  this 
band  is  sometimes  twice  interrupted,  so  that  it  is  represented  by 
three  dots ;  the  abdomen  is  bright  red,  with  the  apex,  a  row  of 
small  dots  on  the  lateral  edges,  and  a  row  of  spots  on  each  side  of 
the  venter,  black;  the  wing-covers  are  black,  with  a  red  arc  opening 
outwards  on  each  ;  the  free  margin  of  the  membrane,  a  pair  of  spots 
on  the  disk,  and  two  or  more  irregular  spots  on  the  basal  margin  of 
the  membrane,  are  snowy  white. 

A  variety  occurs  in  which  the  white  spots  on  the  disk  of  the 
membrane  are  wanting.  This  variety  is  the  most  common  represen- 
tative of  the  Lygaeinae  which  I  find  in  central  New  York.  A  few 
of  the  New  York  specimens  show  the  white  spot ;  while  in  a  large 
series  of  this  species  in  our  collection  from  Arizona  these  spots  are 
invariably  present. 

Lygaus  turcicus. — This  species  is  very  closely  allied  to  the  pre- 
ceding, if  not  identical  with  it.  Here  the  red  spot  on  the  vertex  is 


2IO  AN  INTRODUCTION   TO  ENTOMOLOGY. 

Y-shaped,  and  includes  the  antennal  tubercles.  The  membrane  of 
the  wing-covers  lacks  the  discal  white  spots,  and  the  basal  half  of  the 
clavus  is  red. 

Among  the  many  smaller  representatives  of  this  family  the  fol- 
lowing is  the  best  known : 

The  Chinch-bug,  Blissus  lencopterus. — This  well-known  pest  of 
grain-fields  is  a  small  bug,  which  when  fully  grown  measures  a  little 
less  than  4  mm.  (0.16  in.)  in  length.  It  is  blackish  in  color,  with  con- 
spicuous snowy- white  wing-covers.  There  is  on  the  costal  margin  of 
each  wing-cover  near  the  middle  of  its  length  a  black  spot ;  from  each 
of  these  spots  there  extends  towards  the  head  a  somewhat  Y-shaped 
dusky  line.  The  body  is  clothed  with  numerous  microscopic  hairs. 
In  Fig.  1 80  this  insect  is  represented  natural  size 
and  enlarged.  The  species  is  dimorphic,  there  being 
a  short-winged  form. 

There  are  two  generations  of  the  Chinch-bug  each 
year.     The  insects   winter  in  the  adult  state,  hiding 
FIG.  180.  —  BUS-     beneath    rubbish  of    any  kind;  they  even   penetrate 

sus  leucopterus.  •          «  ,     •  .  . 

forests  and  creep  under  leaves,  and  into  crevices  in 
bark.  In  early  spring  they  emerge  from  their  winter  quarters 
and  pair ;  soon  after  the  females  begin  to  lay  their  eggs  ;  this 
they  do  leisurely,  the  process  being  carried  on  for  two  or  three 
weeks.  The  eggs  are  yellowish  ;  about  500  are  laid  by  a  single  in- 
sect ;  they  are  deposited  in  fields  of  grain,  beneath  the  ground  upon 
the  roots,  or  on  the  stem  near  the  surface.  The  eggs  hatch  in  about 
two  weeks  after  being  laid.  The  newly-hatched  bugs  are  red  ;  they 
feed  at  first  on  the  roots  of  the  plants  which  they  infest,  sucking  the 
juices ;  afterwards  they  attack  the  stalks.  The  bugs  become  full- 
grown  in  from  forty  to  fifty  days.  Before  the  females  of  this  brood 
deposit  their  eggs,  they  leave  their  original  quarters  and  migrate  in 
search  of  a  more  abundant  supply  of  food.  About  this  time  the 
wheat  becomes  dry  and  hard  ;  and  the  migration  appears  to  be  a 
very  general  one.  Although  the  insects  sometimes  go  in  different 
directions,  as  a  general  rule  the  masses  take  one  direction,  which  is 
towards  the  nearest  field  of  oats,  corn,  or  some  other  cereal  or  grass 
that  is  still  in  a  succulent  state.  At  this  time  many  of  the  bugs 
have  not  reached  the  adult  state  ;  and  even  in  the  case  of  the  fully- 
winged  individuals  the  migration  is  usually  on  foot.  In  their  new 
quarters  the  bugs  lay  the  eggs  for  the  second  or  fall  brood. 

Satisfactory  means  of  preventing  the  ravages  of  this  insect  are 


HEMIPTERA.  211 

yet  to  be  discovered.  Something  can  be  done  by  burning  in  au- 
tumn all  rubbish  about  fields,  in  fence-corners,  and  in  other  places 
where  the  bugs  have  congregated  to  pass  the  winter.  The  march- 
ing of  the  spring  brood  into  new  fields  has  been  stopped  by  means 
of  ditches,  as  is  done  with  the  Army-worm.  Some  farmers  have  ac- 
complished the  same  purpose  by  making  a  line  of  gas-tar  on  the 
ground  ;  the  bugs  will  not  pass  such  a  line,  but  it  is  necessary  to  re- 
place it  frequently.  In  some  cases  kerosene  emulsion  can  be  used 
to  advantage. 


Family  XXXI.— BERYTID^:.* 

The  Berytidce  consists  of  a  small  number  of  species,  which  on 
account  of  their  attenuated  forms  are  very  striking  in  appear- 
ance. The  body  is  long  and  narrow ;  the  legs  and  antennae  are  also 
long  and  extremely  slender.  There  is  a  transverse  incision  in  the 
vertex  in  front  of  the  ocelli.  The  antennae  are  four-jointed,  elbowed 
at  the  base  of  the  second  segment,  and  with  the  tip  of  the  first  seg- 
ment enlarged.  The  rostrum  is  four-jointed  ;  and  the  membrane 
of  the  wing-covers  is  furnished  with  a  very  few  veins. 

Only  two  genera  are  catalogued  from 
the  United  States,  each  represented  by  a 
single  species,  Jdlysus  spinosus  and  Neides 
muticus.  These  can  be  separated  as  follows: 

In  Jdlysus  (Fig.  181)  neither  thecorium 
nor  the  venter  is  punctate ;  and  the  ver- 
tex is  not  furnished  with  a  prominent 
spinous  process  extending  cephalad. 
There  is,  however,  a  small  spine  on  the 
scutellum,  and  one  on  each  side  of  the 
thorax  in  front  of  the  coxa.  /.  spinosus 
measures  about  8  mm.  (0.31  in.)  in  length. 

In  Neides  the  corium  and  venter  are 
strongly  punctate;  the  vertex  is  furnished        FlG  ^.-jaiytuss finals. 
with  a  prominent  spinous  process  extend- 
ing cephalad.     This  genus  lacks  the  spines  of  the  scutellum   and 
thorax  characteristic  of  the  preceding  genus. 

*  Berytidse,  Berytus  :  firjpvroS,  Greek  name  of  Beyrout. 


212  AN  INTRODUCTION   TO  ENTOMOLOGY. 


Family  XXXII.— < 

The  Coreidae   is  one  of  the   most  extensive   of  the  families  of 
Heteroptera ;  and  the  members  of  it  vary  greatly  in  form.     Some 
of  the  species  are  among  the  most  formidable  in  appearance  of  all 
of  our  Heteroptera ;  while  others  are  comparatively  weak  and  in- 
conspicuous.    The  family  is  characterized  as  follows :  The  antennae 
are  inserted  above  an  ideal  line  extending  from  the  eye  to  the  base 
of  the  rostrum,  and  are  four-jointed ;  the  vertex  is  not  transversely 
impressed  ;  the  ocelli  are  present ;  the  rostrum  is  four-jointed  ;  the 
scutellum  is  small  or  of  medium  size ;  the  wing-covers  are  usually 
complete,    and     composed    of    clavus,     corium,     and 
membrane ;    the    membrane    is   furnished   with    many 
veins,    which    spring    from    a    transverse    basal   vein, 
FIG.    182.—       and    are    usually     forked    (Fig.    182);    the    tarsi    are 
XiSwJSS.      three-jointed. 

This  family  contains  both  vegetable  feeders  and 
carnivorous  forms ;  in  some  cases  the  same  species  will  feed  upon 
both  insects  and  plants. 

The  most  common  and  best  known  species  is 
the  Squash-bug,  Anasa  tristis.  The  form  of  the 
body  of  the  adult  insect  is  represented  in  Fig. 
183.  In  this  stage  the  insect  appears  blackish- 
brown  above  and  dirty-yellow  beneath.  The 
ground  color  is  really  ochre-yellow,  darkened  by 
numerous  minute  black  punctures.  Upon  the 
head  are  two  longitudinal  black  stripes;  the  lat-  FlG  j83  _Anasa 
eral  margins  of  the  prothorax  are  yellow,  owing 
to  the  absence  along  a  narrow  space  of  the  punc- 
tures ;  and  the  margin  of  the  abdomen  is  spotted  with  yellow  from 
a  similar  cause  ;  the  membrane  of  the  wing-covers  is  black. 

This  species  winters  in  the  adult  state.  In  early  summer  it  lays 
its  eggs  in  little  patches  on  the  young  leaves  of  squash  and  allied 
plants.  The  young  bugs  are  short  and  more  rounded  than  the 
adult  insects.  There  are  several  generations  of  this  species  each 
year. 

This  is  one  of  the  most  annoying  of  the  many  pests  of  the 
kitchen-garden.  The  most  satisfactory  way  yet  devised  for  pre- 
venting its  ravages  is  to  protect  the  young  plants  by  means  of 

*  CorSidae,  Coreus  :  probably  from  coris  (/copzS),  bug. 


HEM  IP  T ERA. 


213 


FlG.  rt^.—Metapodius  femoratus, 
(From  Glover.) 


boxes  or  frames  covered  with  netting.     After  the  plants  have  ob- 
tained a  good  start  they  are  not  easily  destroyed  by  this  bug. 

Mctapodius  femoratus  (Fig.  1 84)  is  a  rep- 
resentative of  a  group  which  contains  the 
largest  members  of  this  family.  This 
species  is  distributed  from  North  Carolina 
to  Florida  and  Mexico.  It  was  observed 
by  Prof.  Trelease  to  destroy  the  Cotton- 
worm  (Aletia). 

Family  XXXIII. — PENTATOMIM!.* 

With  the  Pentatomidce  we  reach  a 
series  of  families,  four  in  number,  in  which 
the  antennae  are  five-jointed.  I  have 
found  no  exception  to  this  character 
within  the  United  States,  although  there 
are  forms  which  occur  just  south  of  our 
border  in  which  the  antennae  are  only  three-  or  four-jointed.  This 
group  of  insects  is  very  easily  recognized  ;  but  the  student  may 
have  at  first  a  little  difficulty  in  separating  the  families.  The 
body  is  short,  broad,  and  rather  thick  The  scutellum  is  al- 
ways large ;  we  find  two  types  of  this  part,  each  characteristic 
of  two  families.  The  first  type  is  presented  by  the  Penta- 
tomidae and  Cydnidae  ;  here  the  scutellum  is  more  or  less  flat- 
tened, and  triangular  in  outline,  being  attenuated  posteriorly.  In 
each  of  these  families  the  lateral  borders  of  the  scutellum  are 
furnished  with  a  groove  into  which  the  wing-cover  fits  when  not  in 
use. 

The  form  of  body  presented  by  the  great  majority  of  the  mem- 
bers of  the  Pentatomidae  is  well  shown  by  Fig.  185. 
It  is  broad,  short,  and  but  slightly  convex ;  the  head 
and  prothorax  form  together  a  triangle.  In  this  family 
the  tibiae  are  unarmed,  or  are  furnished  with  very  fine 
short  spines.  This  is  the  most  available  character  for 
separating  this  from  the  following  family.  Of  the 
Pentatomidae,  the  genus  Dlnidor,  which  occurs  in 
Mexico,  and  certain  other  exotic  forms  have  only 
four-jointed  antennae. 

As  with  the  Coreidae,  the  members  of  this  family  vary  greatly  in 

*  PentatSmidai,  Pentatoma  :  pente  (itevTe\  five  ;  tome  (ro^tj),  section. 


FIG   185.  —  A 
Pentatomid. 


214  AN  INTRODUCTION   TO  ENTOMOLOGY. 

their  habits ;  some  are  injurious  to  vegetation  ;  others  are  preda- 
ceous ;  while  some  species  feed  indifferently  upon  animal  or  vege- 
table matter. 

The  Harlequin  Cabbage-bug,  Murgdntia  histronica. — Among  the 
species  of  the  Pentatomidae  that  feed  upon  cultivated  plants,  the 
Harlequin  Cabbage-bug,  or  "  Calico-back"  as  it  is  called  in  some 
sections,  is  the  most  important  pest.  This  is  a  very  common  insect 
in  the  Southern  States.  It  occurs  from  New  Jersey  southward  and 
westward.  I  have  specimens  from  Colorado,  and  Arizona.  It  feeds 
upon  cabbage,  radishes,  turnips,  and  other  Curciferous  plants  ;  it  is  also 
found  sometimes  on  plants  not  closely  related  to  cabbage.  The 
adult  bug  measures  about  10  mm.  (0.4  in.)  in  length.  It  is  polished 
blue  black,  banded  striped,  and  margined  above  with  yellow,  orange, 
or  red  ;  on  the  venter  it  has  seven  lines  of  yellow  and  orange  spots  ; 
and  the  head  has  generally  two  white  spots  on  the  front.  The  relative 
proportions  of  the  black  and  the  light  colors  vary  greatly  indifferent 
specimens.  This  bug  winters  in  the  adult  state ;  in  early  spring  it 
emerges  and  lays  its  eggs  on  the  young  plants.  The  eggs  are  usually 
attached  to  the  lower  surface  of  the  leaves  in  two  parallel  rows  of 
about  six  each.  The  young  larva  is  of  a  uniform  pale-green  color, 
marked  with  black  ;  with  the  successive  moults  the  various  orange 
markings  appear.  In  the  immature  stages  the  antennae  are  only  four- 
jointed.  This  insect  develops  very  rapidly  ;  the  eggs  hatch  on  the 
third  day  after  they  are  laid ;  and  it  is  said  that  the  bugs  will  pass 
through  all  of  their  moults  and  be  ready  for  reproduction  in  two 
weeks.  There  is  a  series  of  generation  extending  through  the  en- 
tire summer.  This  is  an  exceedingly  difficult  species  to  contend 
against.  Much  can  be  done  by  trapping  the  bugs  that  have 
hibernated  by  placing  turnip  or  cabbage  leaves  in  the  garden  in  early 
spring. 

As  if  to  atone  for  the  destruction  caused  by  their  relative,  the 
Harlequin  Cabbage-bug,  there  are  many  members  of  this  family 
which  aid  the  agriculturist,  by  destroying  noxious  insects.  I  can- 
not, without  going  into  details  inappropriate  here,  point  out  so  that 
they  could  be  recognized  the  predaceous  members  of  this  family. 
And  it  would  hardly  be  worth  while.  It  is  only  in  case  of  excep- 
tional species,  like  that  just  described,  that  these  insects  occur  in  suf- 
ficient numbers  to  invite  the  attention  of  the  agriculturist.  They  are 
usually  found  wandering  singly  over  the  plants  which  they  attack  or 
upon  which  they  search  for  their  prey. 

The  species  of  the  genus  Podisus  have  been  reported  more  often 


.       - 

fftsus    sf>ino- 


HEMIPTERA.  2I- 

than  any  other  as  destroying  the  Potato-beetle,  currant-worms  and 
other  well-known  pests.     The  form  of  the  body  of  members  of  this 
genus  resembles  quite  closely  that  of  the  insect  represented  by  Fig 
1  86.     In  P.  spinosus,   the  best-known   member  of  the 
genus,  the  caudo-lateral  angles  of  the  prothorax  are  pro- 
longed into  spines. 

Among  the  smaller  members  of  this  family  there  are 
two  common  species  which  are  so  well  marked  that 
they  may  be  mentioned  here. 

Cosmopepla  cdrnifex  is  the  more   common   of  the      FlS-. 

fftsus    sf>i 

two  species.  It  measures  about  7  mm.  (0.28  in.)  in  ciove/) 
length  ;  and  is  of  a  shining  black  color,  with  the  body 
densely  punctured.  The  lateral  margin  of  the  body,  including 
the  prothorax,  basal  half  of  wing-covers,  metathorax,  and  abdo- 
men, is  red  or  orange;  the  disk  of  the  pronotum  is  crossed 
by  a  transverse  and  a  longitudinal  line  of  the  same  color;  the 
longitudinal  line  is  widened  at  its  cephalic  end  so  as  to  cover  half  of 
the  cephalic  margin  of  this  segment.  There  are  also  two  red  or 
orange  spots  near  the  tip  of  the  scutellum. 

Mormldea  lugens  is  the  other  species.  This  also  measures  about  7 
mm.  (0.28  in.)  in  length.  The  body  is  densely  punctured  ;  it  is  olive 
brown  above,  and  darker  beneath.  The  lateral  margin,  including  the 
same  parts  as  in  the  preceding  species,  is  light  yellow  ;  the  cephalic 
margin  of  the  prothorax  is  of  the  same  color  ;  and  there  is  a  trans- 
verse yellow  line  on  the  pronotum  a  short  distance  behind  its  front 
margin  ;  the  scutellum  except  its  cephalic  margin  is  also  bordered 
with  yellow. 

Family  XXXIV.—  CYDNID.E.* 

The  characters  of  this  family  have  been  discussed  somewhat  in 
the  characterization  of  the  preceding  one.  In  the 
Cydnidaewe  find  the  outline  of  the  body  more  generally 
oval,  rounded,  or  elliptical,  and  the  form  more  convex, 
than  in  the  Pentatomidae.  The  tibiae  are  closely  armed 
with  strong  spines,  in  rows  (Fig.  187),  and,  with  but  a 
single  known  exception  in  our  fauna,  the  anterior  pair 
are  fitted  for  digging,  being  more  or  less  flattened.  The 
scutellum  is  either  broad  and  bluntly  rounded  or  tri- 
angular, with  the  apex  pressed  down  ;  the  lateral  margins  are  fur- 

*  Cydnidae,  Cydnus  :  Cydnus,  a  proper  name. 


2l6  AN  INTRODUCTION   TO   ENTOMOLOGY. 

nished  with  a  furrow  into  which  the  margin  of  the  wing-cover  fits 
when  not  in  use.  The  antennae  are  five-jointed  except  in  the 
exotic  genera  Adrisa  and  Pachymcroides  ;  the  distal  three  seg- 
ments are  usually  united  by  slender  threads. 

The  species  are  generally  black  or  very  dark  brown.  They  are 
found  burrowing  in  sandy  places,  or  on  the  surface  of  the  ground 
beneath  sticks  and  stones,  or  at  the  roots  of  grass  and  other  herb- 
age. A  European  species  is  said  to  suck  the  sap  from  various  plants 
near  the  ground.  It  is  desirable  that  further  observations  be  made 
upon  the  habits  of  this  family. 


Family  XXXV.  — 

(The  Negro-bugs^] 

This   family   is   represented    in    our   fauna   by   a  single   genus, 

Corimel&na.      They  are   mostly   black,    beetle-like   in    appearance  ; 

some  have  a  bluish  or  greenish  tinge,  and  all  are  very  convex.     The 

form  of  the  body  is  similar  to  that  seen  in  the  next  family.     It   is 

short,  broad,  and  very  convex,  in  fact  almost  hemispherical.     The 

scutellum    is   very  convex,   and    covers    nearly   the   whole   of   the 

abdomen.     At  the  base  of  the  scutellum  there   is  on  each  side  a 

short  furrow  into  which  the  edge  of  the  wing-cover  fits  when  at  rest. 

•*     i          This  character  allies  this  family  to  the  two  preceding, 

jf\          and  separates  it    from   the  following.      These    insects 

]_  ^Jwl  JtV»       infest    various  plants  ;    and    often    injure    raspberries, 

Jl^^i         and  other*  fruit,  by  imparting  a  disagreeable,  bed-bug- 

FIG  iss.-cw-     l*ke  odor  to  them.     Fig.    188  represents  Corimelcena 

meianaatra.      atro,,  somewhat  enlarged  ;  this  is  a  common  and  widely 

distributed  species. 

Family  XXXVI.—  SCUTELLERID.E. 

The  Scutelleridae  resemble  in  the  form  of  their  body  the  pre- 
ceding family.  They  are  turtle-shaped  bugs;  that  is,  the  body  is 
short,  broad,  and  very  convex.  The  scutellum  is  very  large,  cover- 
ing nearly  the  whole  of  the  abdomen.  The  lateral  margin  of  the 
scutellum  is  not  furnished  with  a  groove  for  receiving  the  edge  of 
the  wing  cover,  as  is  the  case  in  the  three  preceding  families.  The 


*  Corimelaenidae,  Corimelaena  :  coris  (KopiS),  bug  ;  melas  (#e'Aa£),  black. 
t  Scutelleridae,  ScutSllera  :  scutdla,  little  plate. 


HEMIPTERA.  211} 

antennae  are  five-jointed,  except  in  the  genus  A ugocoris,  which  occurs 

in   Mexico  and  in  the  West  Indies,  and    in  certain 

\Jth(         South    American    forms;    in  these  they   are  three- 

j  jointed.     Fig.  189  represents  Eurygdster  alterndtus 

|    '•TJI       IX       somewhat    enlarged,  and    serves    to    illustrate  the 

)  Wp?r  ^       typical  form  of  members  of  this  family. 
FIG.  189.— Eurygas-  I  have  met  no  account  of  any  of   our  species  of 

this  family  occurring   in   sufficient  numbers  to   be 
of  economic  importance. 


CHAPTER   IX. 
Order  VI.— NEUROPTERA  * 

(Ant-lions,  Scorpion-flies,  Caddicc-flies,  et  al.) 

The  members  of  this  order  have  four  wings ;  these  are  membra- 
nous, and  usually  furnished  with  numerous  veins.  The  mouth-parts 
are  formed  for  biting  except  in  one  family  (Phryganeidae),  where  they 
are  rudimentary.  The  metamorphosis  is  complete. 

The  term  Neuroptera,  or  nerve-winged  insects,  is  applied  to  the 
members  of  this  order  on  account  of  the  numerous  veins  or  nerves 
with  which  the  wings  are  strengthened.  In  this  character  there  is, 
however,  a  close  resemblance  between  the  Neuroptera  and  the 
Pseudoneuroptera.  Regarding  the  relations  of  these  two  orders  the 
reader  is  referred  to  the  remarks  on  page  62. 

It  is  not  certain  that  the  Neuroptera  as  limited  here  is  a  natural 
group.  One  family,  the  Caddice-flies  (Phryganeidce),  differs  so 
greatly  from  the  other  families  that  it  has  long  been  separated  as  a 
distinct  order;  and  more  recently  it  has  been  proposed  for  similar 
reasons  to  treat  another  family,  the  Scorpion-flies  (Panorpidce),  in  a 
like  manner.  This  multiplication  of  the  orders  has  not  yet  been 
generally  accepted. 

Owing  to  the  great  variations  in  structure  exhibited  by  the  dif- 
ferent families,  it  is  not  easy  to  make  generalizations  regarding  this 
order.  I  will,  therefore,  reserve  the  more  detailed  discussions  of 
the  structure  of  these  insects  for  the  special  treatment  of  the  indi- 
vidual families. 

The  Neuroptera  includes  four  families.  These  can  be  separated 
by  the  following  table  : 

TABLE   OF  FAMILIES   OF  NEUROPTERA.f 

A.  With  well-developed  wings. 

B.  Posterior  wings  with  no  anal  space ;  not  folded. 
C.   Mouth  prolonged  into  a  rostrum.  3.  PANORPID^:. 

*  NeurSptera:  neuron  (vevpov),  nerve;  pteron  (Tfrepor),  wing, 
f  After  Baron  Osten  Sacken  in  Hagen's  Synopsis. 


NEUROPTERA. 

CC.   Mouth  not  prolonged  into  a  rostrum. 
BB.  Posterior  wings  with  a  folded  anal  space.* 
C.  Wings  reticulate.     Prothorax  large. 
CC.   Wings  with  rather  few  transverse  veins. 

AA.  Wingless,  or  with  rudimentary  wings. 
B.  Mouth  prolonged  into  a  rostrum. 
BB.  Mouth  not  prolonged  into  a  rostrum. 


2.9 
2.  HEMEROBIADJE. 

I.   SlALIDJE. 

Prothorax  small. 

4.  PHRYGANEIDJE. 

3-    PANORPIDyfc. 

4.  PHRYGANEID/E. 


Family  I.— < 
( The  Dabson  et  al.) 

There  is  no  common  name  by  which  the  members  of  this  family 
as   a   whole   are    known.      They   are,   however,    easily   recognized. 
Although  the  typical  genus,  Sialis, 
includes  insects   of    moderate    size, 
our  most  common  forms  are  large. 
All  are  characterized  by  having  the 
second  pair  of   wings  with  a  folded 
anal    space,  and   by  having  a   large 
prothorax.      This  segment  is  either 
quadrangular  or  cylindrical  and  long 

The  larvae  of  all  of  the  forms 
occurring  in  the  Eastern  United 
States  are  aquatic,  living  chiefly 
under  stones  in  the  bed  of  swiftly- 
flowing  streams.  They  are  carniv- 
orous. 

This  family  is  represented  in  our 
fauna  by  four  genera.  These  can 
be  separated  by  the  following  table : 

A.  Wings  without  pterostigma  ;  prothorax 

quadrangular. 

B.  No  ocelli.  SIALIS. 

BB.  With  three  ocelli. 
C.  Latero-caudal   angles  of  head  un- 
armed.    Transverse  veins  of  wings 
slender.  CHAULIODES. 

CC.  Latero-caudal  angles  of  head  with  a  sharp  tooth.     Transverse  veins  of 

wings  stout.  CORYDALIS. 

AA.  Wings  with  pterostigma ;  prothorax  cylindrical  and  long.          RAPHIDIA. 

*  The  anal  space  is  absent  in  a  few  Phryganeidae. 
f  Sialidae,  Slalis  :  sialon  (aiahor),  saliva. 


FlG-  ^— 


««•«/*,  ad 


220  AN  INTRODUCTION    TO  ENTOMOLOGY. 

Stalls. — This  genus  includes  the  smaller  of  our  representatives 
of  the  family,  those  having  an  expanse  of  wings  of  about  25  mm. 
(i  in.).  The  prothorax  is  nearly  or  quite  equal  in  width  to  the 
head  ;  there  are  no  ocelli ;  the  antennae  are  filiform  ;  the  wings  are 
irregularly  reticulated  with  stout  veins;  and  the  fourth  segment  of 
the  tarsi  is  dilated  and  bilobed.  Our  common  species  is  S.  in- 
fumdta.  This  is  black,  with  the  head  not  narrowed  posteriorly ;  the 
prothorax  is  a  little  wider  than  the  head ;  and  the  feet  and  wings 
are  black.  I  find  the  larva  of  this  species  common  in  the  swiftly- 
flowing  creeks  about  Ithaca,  adhering  to  the  lower  side  of  stones  in 
the  bed  of  the  streams.  It  resembles  in  form  a  young  Corydalis, 
or  "  Dobson."  It  has  a  pair  of  long  tapering  appendages  on  each 
of  the  first  seven  abdominal  segments,  similar  to  those  of  Cory- 
dalis. It  differs  from  Corydalis  in  that  the  caudal  end  of  the  body 
is  terminated  by  a  very  long  tapering  appendage ;  and  there  are  no 
tufts  of  tracheal  gills.  It  is  probable  that  when  the  larva  is  full 
grown  it  leaves  the  water  and  transforms  in  an  earthen  cell  without 
a  cocoon,  as  is  the  case  with  well-known  European  species. 

Chaullodes. — The  species  of  Chauliodes  are  larger  than  the  mem- 
bers of  the  preceding  genus,  measuring  from  30-60  mm.  (1.2  in.- 
2.4  in.)  in  length,  and  having  an  alar  expanse  of  from  60-100  mm. 
(2.4  in.-4  in.).  They  differ  also  in  having  ocelli ;  three  in  number, 
and  placed  close  together.  This  genus  closely  resembles  the  follow- 
ing one,  but  can  be  distinguished  by  the  characters  given  in  the 
table  above.  The  two  genera  also  differ  in  that  the  caudal  appen- 
dages of  the  male  are  conical  and  simple  in  Chauliodes ;  while  they 
are  in  the  form  of  forceps  in  Corydalis.  The  larva  of  Chauliodes 
also  greatly  resembles  that  of  Corydalis.  The  abdomen  is  furnished 
with  similar  lateral  filaments,  and  anal  pro-legs  furnished  with  hooks. 
But  there  are  no  tufts  of  tracheal  gills  as  in  Corydalis.  The  larva 
of  Chauliodes  are  aquatic,  and  probably  carnivorous. 

Chaullodes  pecticornis  is  a  common  species  with  grayish  wings 
and  feather-like  antennae.  Chauliodes  serricornis  is  also  common  ; 
this  is  a  brownish-black  species  with  the  wings  spotted  with  white, 
and  with  serrate  antennae. 

Corydalis. — The  characters  by  which  this  genus  can  be  recog- 
nized have  been  given  in  the  table  above,  and  in  the  discussion  of 
the  preceding  genus.  We  have  but  a  single  common  species,  the 
Hellgrammite-fly,  Corydalis  cornuta.  This  is  a  magnificent  insect, 
having  an  alar  expanse  of  from  100-135  mm.  (4  in.~5.4  in.).  The 
male  is  remarkable  for  the  great  size  of  its  mandibles,  which  are 


NEUROPTERA.  221 

more  than  half  as  long  as  the  rest  of  the  body.  This  species  is 
common  throughout  the  greater  part  of  the  United  States.  The 
larvae  are  called  "  Dobsons"  by  anglers,  and  are  used  by  them  for 
bait,  especially  for  bass.  Fig.  191  represents  a  fully  grown  Dob- 
son,  natural  size.  There  is  on  each  abdominal  segment  a  pair  of 
long  tapering  appendages  ;  those  of  the  ninth 
abdominal  segment  are  carried  back  so  as  to 
project  from  the  sides  of  a  pair  of  anal  pro- 
legs.  These  pro-legs  project  caudad,  and  are 
furnished  each  with  a  pair  of  claws.  At  the 
base  of  each  lateral  appendage  on  the  first 
seven  abdominal  segments  there  is  a  tuft  of 
hair-like  tracheal  gills.  The  larva  also  has 
spiracles;  a  remarkable  instance  of  an  insect 
provided  with  both  organs  for  aquatic  and 
aerial  respiration.  The  spiracles  are  probably 
not  used  till  the  insect  is  fully  grown  and 
leaves  the  water  to  undergo  its  transforma- 
tions. These  larvae  live  under  stones  in  'the 
bed  of  streams.  They  are  most  abundant  in 
the  swifter  parts  of  the  stream.  They  are 
carnivorous,  feeding  upon  the  larvae  of  Stone- 
flies,  May-flies,  and  other  insects.  When 
about  two  years  and  eleven  months  old,  the 

larva  leaves  the  water  and  makes  a  cell  under  FlG  ^_Corydalis  cornu. 
a  stone  or  other  object  on  or  near  the  '"> larva- 

bank  of  the  stream.  This  occurs  at  Ithaca  during  the  latter  part 
of  May  or  early  in  June.  By  the  middle  of  June  the  majority  of 
these  larvae  have  transformed  to  pupae.  These  are  of  a  yellowish- 
white  color.  They  are  furnished  with  rudimentary  wings  and  legs, 
and  quite  long  antennae.  During  the  last  half  of  June  the  pupae 
change  to  the  adult  state.  The  eggs  are  soon  laid.  These  are 
attached  to  stones  or  to  other  objects  overhanging  the  water. 
They  are  laid  in  blotch-like  masses,  which  are  chalky  white  in  color 
and  measure  from  12  to  20  mm.  in  diameter.  A  single  mass  con- 
tains from  two  thousand  to  three  thousand  eggs.  When  the  larvae 
hatch  they  at  once  find  their  way  into  the  water,  where  they  remain 
till  fully  grown. 

Raphidia.—'NHS  genus  is  represented  in  this  country  only  on  the 
Pacific  Coast.  It  is  distinguished  from  the  other  members  of  the 
family  by  having  the  prothorax  cylindrical,  and  in  having  the  wings 

15 


222  AN  INTRODUCTION    TO  ENTOMOLOGY. 

furnished  with  a  pterostigma.  The  anal  space  of  the  second  pair 
of  wings  is  small.  The  third  segment  of  the  tarsi  is  dilated  and 
bilobed ;  and  the  fourth  is  very  short.  The  abdomen  in  the  female 
is  furnished  with  a  long  ovipositor.  The  larvae  differ  from  all  other 
Sialidae  in  not  being  aquatic ;  they  are  found  under  bark. 

Those  species  of  this  genus  that  have  no  ocelli  have  been  placed 
by  some  writers  in  a  distinct  genus,  Inocellia. 


Family  II.  —  HEMEROBIAD.E.* 
(Ant-lions,  Lace-winged  Flies,  et  al.*) 

The  Hemerobiadae  is  a  family  of  considerable  extent  ;  and  repre- 
sentatives of  it  are  very  common  throughout  our  country.  As  a 
rule  they  are  delicate  insects,  with  large,  gauzy  wings.  These  wings 
are  narrow,  having  no  anal  space  ;  in  this  respect  they  resemble  the 
wings  of  the  Panorpidae.  But  the  members  of  this  family  differ 
from  the  Panorpidae  in  not  having  the  mouth-parts  prolonged  into 
a  rostrum.  The  larvae  ,of  the  Hemerobiadae  are  predaceous  ;  and 
they  are  remarkable  for  having  the  mouth-parts  formed  for  sucking. 
They  thus  form  an  apparent  exception  to  the  characters  of  the  order 
Neuroptera.  The  form  of  these  mouth-parts  is  a  very  unusual  one. 
It  i?  well  shown  in  the  larva  of  the  Ant-lion,  where  these  organs  are 
large  enough  to  be  easily  studied.  The  mandibles  are  very  long  ; 
on  the  ventral  aspect  of  each  there  is  a  furrow  the  entire  length  ; 
into  this  furrow  the  long  and  slender  maxilla  fits.  In  this  way  the 
mandible  and  maxilla  of  each  side  form  a  tube  through  which  the 
blood  of  the  prey  of  the  insect  can  be  drawn. 

Five  sub-families  are  represented  in  our  fauna.  These  can  be 
separated  by  the  following  table  : 

TABLE   OF   SUB-FAMILIES   OF   HEMEROBIADAE. 

A.  Prothorax  not  greatly  elongated  ;  the  three  pairs  of  legs  similar  in  structure. 
B.  Wings  with  very  few  veins,  and  covered  with  whitish  powder. 

i.  CONIOPTERYGIN.E. 

BB.  Wings  with  numerous  veins,  and  not  covered  with  powder. 
C.  Antennae  without  terminal  enlargement. 

D.  Subcostal  vein  joined  to  the  median  before  the  end  of  the  wing;  the 
principal  sector  parallel  to  the  median  vein  and  giving  rise  to  the 
other  sectors.f  (Sisyra,  Polystazchotes.)  2.  HEMEROBIIN^E. 


*  Hemerobiadae,  HemerSbius:  hemera  (fas  pa),  day;  bios  (/S/oS),  life. 
f  For  explanation  of  terms  see  Fig.  71,  p.  73. 


NEUROPTERA. 


223 


DD.  Subcostal  and  median  veins  separate. 

E.  Some  of  the  transverse  veins  between  the  costal   and   subcostal 
forked.     (Micromus,  Hemerobius.}  2.   HEMEROBIIMJE. 

EE.  Transverse  veins  between  the  costal  and  subcostal  veins  simple. 

3.  CHRYSOPIN^E. 

CC.   Antennae  gradually  enlarging  towards  the  end,  or  filiform  with  a  ter- 
minal knob.  4.  MYRMELEOMN.K. 
AA.   Prothorax  greatly  elongated  ;  first  pair  of  legs  fitted  for  grasping. 

5.  MANTISPIN^E. 

Sub-family  I.— CONIOPTERYGIN^E. 
(Mealy-winged  Neuroptera^) 

This  is  a  sub-family  of  limited  extent ;  and  it  includes  only  small 
insects.  They  are  characterized  by  a  very  small  number  of  veins  in 
the  wings,  and  by  having  the  body  and  wings  covered  with  a  whitish 
powder.  The  larvae  are  said  to  have  the  peculiar  form  of  sucking 
mouth-parts  characteristic  of  the  Hemerobiadae ;  and  they  probably 
feed  upon  small  plant-lice. 

Two  genera  have  been  described.  Aleuronia  has  reniform  eyes 
and  ciliated  wings ;  in  Coniopteryx  the  eyes  are  globose  and  the 
wings  are  not  ciliated.  Our  common  species  is  Aleuronia  ^vest^voodi^. 
This  occurs  in  the  adult  state  in  June  and  July ;  it  is  black,  with  the 
abdomen  yellowish;  and  measures  to -the  tip  of  the  wings  2$  mm. 
(o.i  inch). 

Sub-family  II.— HEMEROBIIN^:. 

To  this  sub-family  belong  many  genera,  of  which  several  are  repre- 
sented in  this  country.  The  antennae  are  setiform  or  moniliform 
without  any  terminal  enlargement.  The  wings  are  furnished  with 
numerous  veins,  and  are  not  covered  with  powder.  Our  genera  fall, 
into  two  groups;  the  first  is  represented  by  Slsyra  and  Polystce- 
chotes,  and  the  second  by  Micromus  and  Hemerobius.  These  groups 
are  separated  in  the  table  of  sub-families  given  above.  The  genera 
in  each  group  can  be  separated  as  follows  :  The  costal  space  *  of  the 
front  wings  of  Sisyra  has  no  recurrent  vein  at  the  base;  while  in 
Polystcechotes  the  first  transverse  vein  of  this  space  curves  towards 
the  base  of  the  wing,  and  gives  off  several  branches  in  its  course. 
The  same  difference  exists  between  Micromus  and  Hemerobius ; 
the  former  is  without  the  recurrent  vein,  while  it  is  present  in  the 
latter. 

*  The  costal  space  is  the  area  between  the  costal  and  subcostal  veins. 


224  AN  INTRODUCTION   TO  ENTOMOLOGY. 

The  genus  Sisyra  is  anomalous  in  that  its  larvae  are  aquatic.  We 
have  a  single  species  described  from  Georgia.  This  is  a  small  insect, 
having  an  alar  expanse  of  only  9  mm.  (0.35  inch). 

Polysicechotes  is  confined  to  this  continent.  These  are  larger 
insects,  having  an  alar  expanse  of  from  50  to  75  mm.  (2  to  3  inches). 
They  are  nocturnal,  and  are  attracted  to  lights.  Two  species  have 
been  described.  P.  punctdtus  is  our  most  common  one  ;  it  is  black- 
ish, with  three  longitudinal  lines  on  the  disk  of  the  prothorax,  and 
the  lateral  margins  of  this  segment  yellowish.  P.  vittdtus  is  pale 
yellowish,  with  a  black  stripe  on  the  sides  of  the  thorax,  and  with 
the  abdomen  dark  brown.  The  larva  of  neither  of  these  species  is 
known.  They  are  probably  aquatic. 

Micromus  includes  smallish  species  having  an  alar  expanse  of 
from  10  to  20  mm.  (0.4  to  0.8  inch).  My  personal  experience  leads 
me  to  believe  that  they  are  rare ;  and  I  find  no  published  accounts 
of  the  appearance  and  habits  of  the  larvae. 

Hemerobius  is  much  better  known ;  although  the  spec.ies  of  this 
genus  are  not  common.  More  than  twenty  North  American  species 
have  been  described.  These  are  also  smallish  insects  ranging  in 
alar  expanse  from  8  to  20  mm.  (0.3  to  0.8  inch).  They  occur  in 
forests,  and  especially  on  Coniferous  trees.  The  larvae  bear  a  strong 
resemblance  to  the  Aphis-lions ;  and  like  them  feed  upon  Aphids 
and  other  small  insects.  After  sucking  the  fluids  from  their  victims, 
they  make  a  cloak  for  themselves  of  the  empty  skins. 

Sub-family  III. — CHRYSOPIN.E. 
(Lace-winged  Flies  or  Aphis-lions.} 

Nearly  all  of  the  species  of  this  sub-family  pertain  to  the  genus 
Chrysopa.  These  insects  are  known  in  the  adult  state  as  Lace-winged 


FJG.  192. — Chrysopa,  eggs  on  stalks,  larva,  and  adult 

Flies,  and  in  the  larval  form  as  Aphis-lions.  The  antennae  of  the 
adult  are  long  and  setaceous ;  the  venation  of  the  wings  resembles 
somewhat  that  of  the  preceding  sub-family ;  but  the  subcostal  and 


NEUROPTERA. 


225 


median  veins  are  separate,  and  the  transverse  veins  of  the   costal 
space  are  not  forked. 

The  lace-winged  Flies  are  very  common  insects  throughout  the 
summer  months  upon  herbage  and  the  foliage  of  trees.  They  are 
usually  of  a  light  green  color  or  yellowish.  While  alive  their  eyes 
are  very  bright ;  and  on  this  account  they  have  also  received  the 
popular  name  of  Golden-eyed  Flies.  Some  species,  when  handled, 
emit  a  very  disagreeable  odor.  A  remarkable  fact  in  the  history  of 
these  insects  is  the  way  in  which  the  female  cares  for  her  eggs. 
When  about  to  lay  an  egg  she  emits  from  the  end  of  her  body  a 
minute  drop  of  a  tenacious  substance  ;  this  is  drawn  out  into  a 
slender  thread  by  lifting  the  abdomen :  then  an  egg  is  placed  on  the 
summit  of  this  thread.  The  thread  dries  at  once  and  firmly  holds 
the  egg  in  mid-air.  These  threads  are  usually  10  to  15  mm.  (0.4  to  0.6 
inch)  in  length,  and  occur  singly  or  in  groups.  It  is  probable  that 
this,  placing  of  the  eggs  on  stalks  protects  them  from  the  ravages  of 
predaceous  insects,  including  the  aphis-lions  themselves.  When  the 
young  aphis-lion  hatches  it  crawls  down  the  thread  that  held  up  the 
egg,  and  starts  in  quest  of  some  small  insect  or  egg  which  it  can 
feed  upon.  While  doing  so  it  may  wander  through  a  forest  of  egg- 
stalks,  not  observing  the  eggs  far  above  it.  The  larvae  are  spindle- 
form,  and  have  long,  sickle-shaped  mandibles.  They  feed  chiefly  on 
plant-lice,  but  will  eat  such  other  injects  as  they  can  overcome.  The 
cocoon  in  which  the  pupa  state  is  passed  is  spherical,  and  composed 
of  dense  layers  of  silk.  In  order  to  emerge  the  insect  cuts  a  circular 
lid  from  one  side  of  the  cocoon. 

Sub-family  IV. — MYRMELEONIN^:. 
(Ant-lions  et  al.} 

The  members  of  this  sub-family  can'be  distinguished  from  other 
Hemerobiadse  by  the  form  of  the  antennae.  Two  types  of  antenna? 
exist  in  the  sub-family,  but  in  each  the  organs  are  enlarged  at  or 
near  the  tip ;  while  in  other  Hemerobiadae  the  antennas  are  with- 
out a  terminal  enlargement. 

The  genera  of  this  sub-family  constitute  two  groups,  each  of 
which  is  represented  in  our  fauna  by  a  well-known  genus.  These 
two  genera  include  nearly  all  of  our  species.  The  first  group  is 
represented  by  Myrmeleon.  Here  the.antennse  are  short  and  gradu- 
ally thickened  towards  the  tip.  In  the  second  group,  represented 


226  AN  INTRODUCTION    TO   ENTOMOLOGY. 

by  Ascdlaphus,  the  antennae  are  long,  filiform,  and  suddenly  enlarged 
at  the  end. 

The  Ant-lions,  Myrmeleon. — This  is  a  large  genus ;  Hagen,  in 
his  Synopsis  published  in  1861,  describes  twenty-five  American 
species.  The  adult  insects  are  graceful  creatures,  with  long,  narrow, 
delicate  wings  and  slender  bodies.  The  larvae  have  broad  and 
somewhat  depressed  bodies  which  taper  towards  each  end.  The 
form  of  the  mouth-parts  has  been  described  in  the  generalizations 
regarding  the  Hemerobiadae.  The  interesting  habits  of  these  larvae 
have  attracted  much  attention  since  the  earliest  times.  They  live  in 
sandy  places,  where  they  dig  pitfalls  for  trapping  their  prey.  In 
making  these  pitfalls  the  sand  is  thrown  out  by  an  upward  jerk  of 
the  head,  this  part  of  the  body  serving  as  a  shovel.  The  pits  differ 
greatly  in  depth,  according  to  the  nature  of  the  soil  in  which  they 
are  made.  Their  sides  are  as  steep  as  the  sand  will  lie.  When  an 
ant,  or  other  wingless  insect,  steps  upon  the  brink  of  one  of  these 
pits,  the  sand  crumbles  beneath  its  feet,  and  it  is  precipitated  into 
the  jaws  of  the  ant-lion,  which  is  buried  in  the  sand,  with  its  jaws  at 


FIG.  193. — Myrmeleon. 

the  bottom  of  the  pit.  In  case  the  ant  does  not  fall  to  the  bottom 
of  the  pit,  the  ant-lion  undermines  it  by  throwing  out  some  sand 
from  beneath  it.  I  have  even  seen  an  ant-lion  throw  the  sand  in 
such  a  way  that  in  falling  it  would  hit  the  ant  and  tend  to  knock  it 
down  the  side  of  the  pit.  These  larvae  can  be  easily  kept  in  a  dish 
of  sand,  and  their  habits  watched.  The  pupa  state  is  passed  in  a 
spherical  cocoon,  made  of  sand  fastened  together  with  silk,  and 
neatly  lined  with  the  same  material.  This  silk  is  spun  from  a  spin- 
neret, placed  at  the  caudal  end  of  the  body,  the  caudal  part  of  the 
alimentary  canal  being  transformed  into  a  silk  gland.  The  food  of 


NEUROPTERA.  22; 

these  larvae  is  of  such  a  nature  that  it  can  all  be  absorbed,  and  thus 
the  rectum  is  not  needed  for  the  passage  of  waste  matter. 

Ascdlaphtis.—A.s  already  stated,  this  genus  differs  from  the  ant- 
lions  in  the  form  of  its  antennae.  The  body  is  short,  and  the  wings 
are  less  densely  veined  than  in  Myrmeleon.  The  early  stages  of  our 
species  have  not  been  observed.  In  case  of  certain  European 
species  the  eggs  are  laid  upon  the  stems  of  grass ;  and  the  larvae 
live  upon  the  ground,  hiding  under  stones,  and  seizing,  by  stepping 
forward,  insects  that  pass  near  them. 

Sub-family  V. — MANTISPIN^:. 
(The  Mantis-like  Neuroptera.) 

This  remarkable  sub-family  is  represented  in  our  fauna  by  a  single 
genus,  Mantispa.  These  insects  present  an  unusual  form  of  the 
prothorax  and  the  first  pair  of  legs;  a  form  that  strikingly  resembles 
the  shape  of  these  parts  in  the  family  Mantidae  of  the  order  Orthop- 
tera.  The  prothorax  is  elongated,  cylindrical,  and  more  or  less 
trumpet-shaped.  The  first  pair  of  legs  are  enlarged  and  fitted  for 
grasping.  The  wings  are  narrow,  the  two  pairs  similar;  and  the 
costal  and  subcostal  veins  are  confluent  near  the  middle  of  the  costal 
margin. 

As  indicated  by  the  form- of  the  grasping  legs,  the  adult  Mantispa 
resembles  the  true  Mantis  in  its  predaceous  habits.  The  trans- 
formations of  these  insects  are  of  unusual  interest.  It  was  acci- 
dentally discovered  that  the  larvae  were  parasitic  in  the  egg-sacs  of 
spiders  of  the  genus  Lycosa.  These  are  the  large  black  spiders  that 
are  common  under  stones,  and  which  carry  their  egg-sacs  with 
them.  Brauer  obtained  eggs  from  a  female  Mantispa  kept  in  con- 
finement. These  eggs  were  rose-red  in  color,  and  fastened  upon 
stalks,  like  the  eggs  of  Chrysopa.  The  eggs  were  laid  in  July  ;  and  the 
larvae  emerged  21  days  later.  The  young  larvae  are  very  agile  crea- 
tures, with  a  long,  slender  body,  well-developed  legs,  and  long, 
slender  antennae.  They  pass  the  winter  without  food.  In  the 
spring  they  find  their  way  into  the  egg-sacs  of  the  above-named 
spiders.  Here  they  feed  upon  the  young  spiders;  and  the  body 
becomes  proportionately  thicker.  Later  the  larva  moults  and  un- 
dergoes a  remarkable  change  in  form,  becoming  what  is  known  as 
the  second  larva.  In  this  stage  the  body  is  much  swollen,  resem- 
bling in  form  the  larva  of  a  bee.  The  legs  are  much  reduced  in 
size ;  the  antennae  are  short ;  and  the  head  is  very  small.  When 


228  AN  INTRODUCTION   TO  ENTOMOLOGY. 

fully  grown  this  larva  measures  from  7  to  10  mm.  (0.3  to  0.4  in.)  in 
length.  It  then  spins  a  cocoon,  and  changes  to  a  pupa  within  the 
skin  of  the  larva.  Later  the  larval  skin  is  cast  ;  and,  finally,  after 
being  in  the  cocoon  about  a  month,  the  pupa  becomes  active,  pierces 
the  cocoon  and  the  egg-sac,  crawls  about  for  a  time,  and  then 
changes  to  the  adult  state. 

Family  III.  —  PANORPID.E.* 
Order  MECOPTERAf  of  some  authors. 

(Boreust  Scorpion-flies,  et  at.) 

This  is  a  small  family  ;  but  it  is  composed  of  very  remarkable 
insects.  The  most  striking  character  common  to  all 
is  presented  by  the  mouth.  This  is  prolonged  into 
a  rostrum,  as  shown  in  the  figure.  The  body  is 
cylindrical  or  conical  ;  the  head  is  exserted  ;  the 
prothorax  is  small;  and  the  tarsi  are  five-jointed. 
So  far  as  is  known  the  members  of  this  family 
are  carnivorous.  There  are  only  four  described 
genera.  These  can  be  separated  by  the  following 
table  : 

FIG.     194.  —  Head 
and    tail   of    Pa- 

A.  Wingless  or  with  rudimentary  wings.  BOREUS. 


AA.  With  well-developed  wings. 
B.  Wings  narrow  ;  antennae  setaceous. 

C.  Tarsi  with  two  serrated  claws.  PANORPA. 

CC.  Tarsi  with  a  single  simple  claw.  BITTACUS. 

BB.  Wings  broad  ;  antennae  short,  thick,  the  apex  narrowed.  MEROPE. 

Boreus.  —  Among  the  few  insects  that  occur  on  the  snow,  in  the 
winter,  in  our  Northern  States,  are  two  species  of  the  genus  Boreus. 
In  this  genus  the  wings  of  the  female  are  very  rudimentary  ;  those 
of  the  males  are  about  half  as  long  as  the  abdomen,  narrow,  stiff, 
and  entirely  useless  for  flight.  Boreus  nivoriundus,  the  Snow-born 
Boreus,  is  shining  black  or  brownish  black,  with  the  rudimentary 
wings,  thorax  above,  and  the  rostrum  and  ovipositor  excepting  their 
tips,  tawny.  The  male  measures  3  mm.  (0.12  in.)  in  length;  the  fe- 
male, including  the  ovipositor,  4^  mm.  (0.16  in.).  The  Midwinter 
Boreus,  B.  brumdlis,  is  smaller;  the  male  measuring  2\  mm.  (o.i  in.), 
and  the  female  3  mm.  (0.12  in.),  in  length.  This  species  is  deep  black- 

*  Panorpidae,  Panorpa:  pan  (Ttdr),  all;  horpe  =  harpe  (ap-Jtrf),  a  sickle. 
f  MecSptera,  incorrectly  written  Mecaptera:  mecos  (jLiifKoS),  length  \pteron  (nrepov), 
wing. 


NEUROPTERA.  22Q 

green  ;  with  the  legs,  antennae,  rostrum,  and  ovipositor  black,  and 
the  rudimentary  wings  brownish  black.  Both  species  are  found 
on  the  snow  throughout  the  entire  winter.  They  also  occur  in  moss 
on  tree-trunks.  It  is  not  known  whether  they  feed  on  the  moss  or 
upon  Thysanurians  and  other  small  insects  which  they  find  there. 
These  insects  have  long  legs,  and  are  able  to  leap  to  a  limited  ex- 
tent. The  females  are  furnished  with  a  long,  curved  ovipositor,  re- 
sembling  that  of  a  cricket.  The  early  stages  of  our  species  liave 
not  been  studied.  The  larva  of  a  European  species  has  been  found 
throughout  the  summer  in  the  ground  and  upon  stones  under  Liver- 
worts. 

The  Scorpion-flies,  Panorpa.—1\&<&  are  our  most  common  rep- 
resentatives of  the  family.  They  are  called  scorpion-flies  on  account 
of  the  peculiar  form  of  the  caudal  part  of  the  abdomen  of  the  male. 
This  at  first  sight  suggests  the  corresponding  part  of  a  scorpion  ; 
but  in  reality  the  form  is  very  different.  The  last 
segment,  instead  of  ending  in  a  sting  like  that  of  a 
scorpion,  is  greatly  enlarged,  and  bears  a  pair  of  clasp- 
ing organs.  The  wings  are  narrow,  but  are  well 
developed,  being  longer  than  the  body.  In  our 
more  common  species  they  are  yellowish  spotted 
with  brownish  black.  The  early  stages  of  several 
European  species  have  been  studied.  The  eggs  F'G-  195-— **«««•- 
are  laid  in  a  mass  in  a  shallow  hole,  which  the  female 
bores  with  her  abdomen  in  damp  earth.  The  larvae  are  remarkable 
on  account  of  their  great  resemblance  to  caterpillars.  *  Not  only  is  the 
form  of  the  body  like  that  of  Lepidopterous  larvae,  but  the  abdomen 
is  furnished  with  fleshy  prop-legs.  There  are,  however,  eight  pairs 
of  these  ;  while  caterpillars  never  have  more  than  five  pairs.  The 
larvse  which  were  kept  in  confinement  were  fed  raw  beef ;  they  made 
horseshoe-shaped  mines  in  the  earth,  one  end  of  which  opened  be- 
neath the  meat.  Their  natural  food  is  unknown. 

Bittacus. — The  insects  of  this  genus  resemble  the  scorpion-flies 
in  having  long,  narrow  wings,  three  ocelli,  and  very  slender,  seta- 
ceous antennae.  But  the  caudal  appendages  of  the  male  are  not 
enlarged  as  in  Panorpa.  The  legs  of  Bittacus  are  very  long ;  this 
with  the  narrow-wings  and  slender  abdomen  cause  these  insects  to 
resemble  Crane-flies.  They  are  predaceous,  the  European  species 

*  The  larvae  of  three  species  are  figured  by  Brauer,  Verhandl.  der  k.  k.  zool.  bot. 
Gesellsch.,  Band  XIII.  taf.  13. 


23O  AN  INTRODUCTION    TO   ENTOMOLOGY. 

having  been  observed  to  capture  and  destroy  flies.  Brauer  figures 
the  larva  of  one  species,  and  represents  it  with  six  true  legs  and 
eight  pairs  of  conical  prop-legs.  Unlike  the  larvae  of  Panorpa,  this 
did  not  mine  in  the  ground,  but  remained  on  the  surface  hiding 
under  dry  leaves  and  other  rubbish. 

Merope. — This  genus  was  established  for  a  very  rare  and  remark- 
able species.  The  wings  are  broad,  with  many  transverse  veins) 
the  ocelli  are  absent ;  the  eyes  are  large,  kidney-shaped,  and  united 
at  the  vertex ;  the  antennae  are  short,  thick,  and  with  the  apex  nar- 
rowed. The  abdomen  of  the  male  has  very  large  forceps. 

Family  IV.— PHRYGANEID^E.* 

Order  TRICHOPTERA  of  some  authors.! 

(Caddice-flies^) 

The  Caddice-flies  are  moth-like  insects,  which  are  common  in  the 
vicinity  of  streams,  ponds,  and  lakes  ;  and  they  are  also  frequently 

attracted  to  lights  at  night.  But  the  larvae 
of  these  insects  are  much  better  known 
than  the  adults ;  for  the  curious  houses 
of  the  caddice-worms  have  attracted  at- 
tention wherever  there  are  observers  of 

FIG.  196. — Caddice-ny. 

insects. 

In  the  adult  insect  the  body-wall  is  soft,  being  membranous  or  at 
the  most  parchment-like,  and  is  thickly  clothed  with  hairs.  There 
are  usually  four  ample  wings.  These  are  membranous ;  but  the 
anterior  pair  are  more  leathery  than  the  posterior.  When  not  in 
use  they  are  folded  against  the  sides  of  the  abdomen,  in  an  almost 
vertical  position,  and  give  the  insect  a  narrow  and  elongated  appear- 
ance. The  wings  are  more  or  less  densely  clothed  with  hairs.  In 
some  cases  the  hairs  are  scale-like  in  form.  The  second  pair  of 
wings  are  generally  broader  than  the  front  wings,  and  are  often  longi- 
tudinally folded  in  repose.  All  have  numerous  longitudinal  veins  ; 
but  the  transverse  ones  are  few. 

The  head  is  small ;  the  antennae  are  sectaceous,  and  frequently 
several  times  as  long  as  the  body;  the  labium  is  usually  elongate; 
the  mandibles  are  mere  tubercles  at  the  base  of  the  labium  ;  the 
maxillae  are  small,  and  ordinarily  furnished  with  an  obtuse  maxillary 

*  Phrygangidae,  Phryganea:  phryganon((ppvyavor},  a  dry  twig, 
f  TrichSptera:  thrix  (Opi^),  a  hair;  pteron  (rtrepov),  a  wing. 


NEUROPTERA. 


231 


lobe ;  the  maxillary  palpi  are  well  developed,  and  furnish  characters 
which  are  much  used  in  classification  ;  the  labium  is  usually  well 
developed,  and  bears  three-jointed  palpi. 

The  females  deposit  their  eggs  in  masses  enveloped  in  a  gelati- 
nous covering.  These  are  often  found  adhering  to  the  end  of  the 
body  in  captured  specimens.  It  is  supposed  that  these  eggs  are 
usually  deposited  on  aquatic  plants ;  but  it  is  known  that  in  some 
cases  the  females  descend  below  the  surface  of  the  water  to  oviposit. 

The  larvae  are  long,  cylindrical,  soft-bodied,  and  furnished  with 
six  well-developed  thoracic  legs  and  a  pair  of  anal  legs.  The  abdo- 
men bears  a  greater  or  less  number  of  hair-like  tracheal  gills.  These 
larvae  protect  themselves  by  building  a  case  about  the  body,  in  which 
they  live  during  the  larval  and  pupal  stages.  These  cases  vary 
greatly  in  form,  and  in  the  materials  used  in  their  construction  ;  but 
in  general  those  made  by  the  larvae  of  any  given  species  are  very 
similar. 

One  of  the  most  interesting  topics  which  a  young  entomologist 
can  take  for  study  is  the  habits  of  these  insects.  The  larvae  can  be 
easily  found  throughout  our  country.  Many  species  can  be  kept  in 
aquaria;  but  others,  those  that  live  in  swiftly-flowing  water,  must  be 
observed  in  their  native  haunts.  I  will  indicate  a  few  of  the  general 
features  in  the  economy  of  these  insects.  The  facts  given  here  can 
be  easily  supplemented  by  any  careful  observer. 

Among  the  simplest  of  the  various  forms  of  houses  built  by 
caddice-worms  are  those  made  by  certain  species  that  live  under 
stones  in  rapid  streams.  These  consist  merely  of  a  few  pebbles 
fastened  to  the  lower  surface  of  a  larger  stone  by  threads  of  silk. 
In  the  space  between  these  stones  the  worm  makes  a  more  or  less 
perfect  tube  of  silk,  within  which  it  lives.  Very  little  respect  for 
the  architectural  skill  of  these  builders  is  commanded  by  their  rude 
dwellings.  But  if  one  looks  a  little  farther,  something  will  be  found 
that  is  sure  to  excite  admiration.  The  dweller  within  this  rude  re- 
treat is  a  fisherman  ;  and  stretched  between  two  stones  near  by  can 
be  seen  his  net.  This  is  made  of  threads  of  silk  extending  in  two 
directions  at  right  angles  to  each  other,  so  as  to  form  meshes  of  sur- 
prising regularity.  It  is  as  if  a  spider  had  stretched  a  small  web  in 
the  water  where  the  current  is  the  swiftest.  In  the  streams  about 
Ithaca  these  caddice-worm  nets  are  very  abundant.  They  occur  in 
the  rapids  between  stones,  but  are  to  be  found  in  greater  numbers 
along  the  brink  of  the  falls.  Here  they  are  built  upon  the  surface 
of  the  rock,  in  the  form  of  semi-elliptical  cups,  which  are  kept  dis- 


232  AN  INTRODUCTION    TO   ENTOMOLOGY. 

tended  by  the  current.  Much  of  the  coating  of  dirt  with  which 
these  rocks  are  clothed  in  summer  is  due  to  its  being  caught  in  these 
nets.  I  have  not  yet  observed  the  owners  of  the  nets  taking  their 
prey  from  them  ;  but  I  cannot  doubt  that  they  are  made  to  trap 
small  insects  or  other  animals  that  are  being  carried  down  stream, 
for  the  larvae  of  the  sub-family  to  which  these  net-builders  belong, 
the  Hydropsychince,  are  known  to  be  carnivorous.  It  should  be 
noted  here,  however,  that  the  greater  number  of  caddice-worms  are 
herbivorous. 

There  are  many  caddice-worms  that  build  their  cases  of  stones ; 
some  of  these  cases  are  very  regular  in  form.  One  of  the  common 
kinds  resembles  a  slightly  tapering  cornucopia,  made  of  small  grains 
of  sand,  cemented  together  with  great  regularity.  Another  consists 
of  a  shorter  tube,  to  each  side  of  which  are  fastened  one  or  two 
larger  stones,  as  if  to  keep  it  in  position  (Fig.  197).  But  more  re- 


1 


FIGS.  197,  198.— Cases  of  Caddice-worms. 


markable  than  either  of  these  is  the  case  (Fig.  198)  which  sc  closely 
resembles  in  form  the  shell  of  a  snail  that  it  has  been  described  as 
such  by  several  conchologists. 

We  find  among  the  caddice-worms  carpenters  as  well  as  masons. 
And  there  exists  among  the  builders  of  wood  as  great  a  variety  of 
architectural  tastes  as  among  the  builders  of  stone.  Probably  the 
most  familiar  of  the  forms  of  cases  made  of  wood  is  that  represented 
in  Fig.  199.  This  is  made  of  irregular  pieces  of  wood  arranged  in  a 


FIGS.  199,  200.— Cases  of  Caddice-worms. 


longitudinal  manner.     Much  more  likely  to  attract  attention  is  the 
case  composed  of  sticks  placed  at  right  angles  to  the  body  (Fig.  200). 


NEUROPTERA. 

These  remind  one  of  the  cob-houses  of  our  childhood  Fortunately 
the  species  that  make  this  style  of  case  live  in  stagnant  water  and 
may,  therefore,  be  kept  alive  in  aquaria.  A  case  closely  resembling 
this  in  plan  but  differing  in  appearance  is  made  of  bits  of  moss 
Sometimes  leaves  are  used ;  these  are  either  fastened  so  as  to  form 
a  flat  case ;  or  are  arranged  in  three  planes,  so  as  to  form  a  tube,  a 
cross  section  of  which  is  a  triangle. 

Whether  stones  or  wood  are  used,  the  material  is  fastened  to- 
gether  by  silk,  which  the  larvae  spin  from  the  mouth  in  the  same 
manner  as  caterpillars.  In  some  species  the  case  is  composed  en- 


FIG.  201. — Case  of  Caddice-worm. 

tirely  of  silk.  Fig.  201  represents  the  form  of  such  a  case,  which  is 
common  in  Cayuga  Lake. 

Before  transforming  to  pupae,  the  caddice-worms  partially  close 
their  cases,  so  as  to  keep  out  intruders;  but  provision  is  made  for 
the  ingress  of  water  for  respiration.  Thus  the  owner  of  the  silken 
case  to  which  reference  has  just  been  made,  when  ready  to  trans- 
form, fastens  its  case  to  a  stem  of  the  grass  which  grows  in  the 
lake,  and  then  closes  the  entrance  to  the  case  with  a  lid  having  a 
slit-like  opening  in  the  centre.  The  worms  making  the  cases  shown 
in  Fig.  199  build  a  grating  in  each  end  of  the  case. 

It  would  naturally  be  supposed  that  the  caddice-worms  would 
escape  the  attacks  of  Ichneumon-flies,  living  as  they  do  beneath 
water,  and  within  well-built  tubes.  But  this  is  not  so.  And  curi- 
ously enough,  in  certain  species  at  least,  the  parasitized  individuals 
differ  from  others  in  fastening  their  cases  by  means  of  a  long  band, 
when  about  to  transform,  instead  of  attaching  them  directly  to  the 
supporting  object. 

In  the  Phryganeidae  we  find  another  group  which  differs  in  such  important 
characters  from  the  most  nearly  allied  insects  that  many  entomologists  believe 
it  should  be  classed  as  a  distinct  order ;  and  long  ago  the  name  Trichoptera  was 
proposed  for  this  order.  The  rudimentary  mouth-parts  of  the  adult  caddice- 
flies  and  the  structure  of  the  wings  separate  them  from  the  other  Neuroptera, 
and  suggest  affinities  with  the  Lepidoptera ;  on  the  other  hand,  the  anal  legs  of 
the  larvse  with  hooked  claws  resemble  those  of  the  Sialidae.  As  indicating  the 
strength  of  the  tendency  to  recognize  the  order  Trichoptera,  it  is  only  necessary 
to  name  Hagen,  McLachlan,  and  Brauer  as  among  those  that  share  this  view. 


234 


AN  INTRODUCTION    TO   ENTOMOLOGY. 


The  American  species  of  the  Phryganeidse  have  not  been  monographed. 
One  hundred  and  fifty  species  are  described  in  Hagen's  Synopsis  of  the  North 
American  Neuroptera;  comparatively  little  has  been  written  regarding  the 
American  forms  during  the  quarter-century  that  has  elapsed  since  the  appear- 
ance of  that  work.  The  student  who  wishes  to  make  a  special  study  of  this 
group  should  possess  the  great  work  of  Robert  McLachlan,  A  Monographic 
Revision  and  Synopsis  of  the  Trichoptera  of  the  European  Fauna.  There  is 
also  a  paper  by  Friedrich  Brauer  which  is  very  useful.  This  is  entitled  Ver- 
zeichniss  der  bisjetzt  bekannten  Neuroptera  im  Sinne  Lznne's,  and  is  published 
in  the  Verhandlungen  der  Zoologisch-Botanischen  Gesellschaft,  XVIII.  (1868). 
It  contains  analytical  keys  to  the  sub-families,  and  to  all  of  the  genera  described 
at  that  time. 


14  DAY  USE 

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BIOLOGY  LIBRARY 

TEL.  NO.  642.2532 

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